I don’t know if I can be objective because I’ve never used a roof box before.
However, I’ll share what I experienced.
I put this 470-liter one on a 2021 Ford Kuga diesel.

On the positive side, if I didn’t have it, the trip wouldn’t have happened. I put the following inside:
2 large beach chairs
2 small ones
2 umbrellas
A bag with buckets
A children’s scooter
A children’s mat
and three supermarket bags with clothes.

Also, you don’t dirty the car with dirt. Whatever gets dirty, you throw in there.

Nice design.

And it doesn’t add much height because the bars “fit” underneath the roof box. I’m at 2.10 with tall bars.

The double opening helps a lot.

It hardly changes the car’s behavior at all.

On the negative side, having a quiet car like the Kuga, where you really whisper and the other person can still hear you even past 160, the roof box can be heard from 100 and up, and past 130 it makes quite a bit of noise. We were speaking quite loudly to hear each other.
Many will say that the manufacturer sets 130 as the limit. Okay, I was going around that speed too, +-10, but it was very audible from 100 and up.

But as I said above, I don’t know whether compared to others it is quieter.
The truth is that my trip became noisier and consumption went up from 6.6 to 7.2. On a steady trip at 130-140 on the Egnatia Highway.
But without it, I simply wouldn’t have gone on vacation.
You gain some, you lose some.

When installing it, spray WD-40 on the locks because they get very stiff and an accident could happen, like a key breaking inside.

I have it permanently in a Nissan Pulsar for 2.5 years and it has served me very well.
The noise at 130-140 doesn't bother me and the difference in consumption is minimal (0.2).
Summer: 4-5 aluminum chairs, children's toys, and 3 umbrellas.
Winter: usually skates and bicycles.
On a trip, you can take whatever you want with you and still have space left.
For parents (which probably interests you more), I have loaded mostly the following: a children's bed and mattress, a folding stroller, a large high chair, a balance bike, and a scooter, 2 garbage bags with dirty clothes, and 2 small suitcases.
Just be careful to put weight up to 30-40 kg or a little more if you have good bars or rails.
Currently, no damage from sun, rain, and sand.
The double opening is convenient, and if the key is not locked properly, it won't come out.
For those interested in transporting children's bicycles, be aware that due to the handlebar, it can fit a 14-inch one with caution in the installation, so I don't consider it a solution for their transportation, only in case of necessity.
I bought it for 380€ with an invoice, and I believe it was more than value for money.

I wasted many hours and days searching for the ideal roof box.

So stop fooling yourselves, there is no car accessory that changes the aerodynamics and is completely silent.

Understand this.

Choosing the right roof box is subjective and a matter of personal preference.

Even the wind deflectors (heko) that I have on my car make noise after 90 km/h, you hear a slight noise (like when it's windy on the road).

I have mentioned all of the above for a reason.

Regarding the roof box, it meets my tastes and needs 100%.

It is of high quality.

It is beautiful (more beautiful on the car than in the photos).

It is huge (for me).

It is "silent" (I will explain).

It is very easy to install and remove (lever mechanism).

It has extra reinforcement with aluminum bars underneath for connection to the roof bars and inside the locks (6 locking points).

It opens from both sides.

Now, onto the most serious issue.

Is it silent???

Yes... It is... as silent as such an accessory can be considered. Which means that after 110 km/h you hear something, but only if you have your mind focused on it while driving and if you are "curious" like me, who closed the radio and a/c to notice the difference.

It makes some noise (as expected and normal), but nothing that bothers or gives you a headache.

Personally, I hear the wind deflectors more than the roof box.

It was installed on a Fiat Tipo sedan (diesel 1.3) with Menabo roof bars.

Despite the 530 liters of storage space, you always need extra space when you have 2 children.

I don't have a clear picture of the fuel consumption, but the roof box will definitely affect it.

Update 20/08: The fuel consumption has increased by about 1 to 1.5 liters... Diesel 1.3 at a speed of 125 km/h fully loaded with a/c. I saw an increase from 4.5 to 4.7 liters, which is usually what I have, to 5.7 to 5.9 liters

First of all, let me start with the basics:
Impeccable and professional service from the beginning to the end of the purchase, as I tried different options until we found the best combination for roof bars - roof box for my BMW SERIES 1 DIESEL 1.5 2018.
In terms of appearance, the car is very beautiful, something I did not expect (in fact, I have heard positive comments and questions about the roof box).
On my first outing, not only did all the baby essentials fit comfortably, but there was also almost one-third of the space left.
On an open road, there was no disturbance from noise up to the manufacturer's kilometers (130), and a couple of times when I forgot and went a little over, only the sound of the wind was heard (which is normal for a full roof box).
I cannot comment on fuel consumption as the car is an automatic diesel with eco mode driving option... so it would probably be wrong to mention numbers.
As with everything, time is the best judge, but I believe that with the after-sale service of Nifoudis Auto-Moto, there will be no problem.

...without previous experience with a roof box, I can say that I have no hesitation in recommending it for purchase! Installed on a 2019 Ford Fiesta ST-Line with simple iron roof bars, the Hermes roof box cost €90. I was looking for something not too big and had set a limit of 400 liters since the car is not the largest, and I thought it would be like a bulky chest on top of the car..... luckily they convinced me to get a larger one and I don't regret it for a moment. I immediately went on a 1000km trip and didn't encounter any issues. It has the perfect shape, it doesn't make any noise, in fact, you can barely hear the bars, and even then, very little. Overall, you can hardly hear anything.

Positive points:
- The construction seems to be of very good quality and durable plastic, unlike cheaper ones that would fade in a year under the sun. Of course, the sun and rain can damage everything, and at some point, it will show signs of wear, but I am sure it will last longer due to the good quality materials.
- It has a lightweight lid that lifts up and stays high without the fear of it falling and trapping your hand inside.
- It has straps inside, so no matter what you put in, you can tighten and secure it to prevent things from moving around and making noise, as well as not shifting the center of gravity. At most, you might need to buy one or more additional straps if you have a lot of things. Since I fill it up, I don't even tighten the straps because there are so many things that they can't move anywhere.
- Also, the 4 round clamps inside don't require any tools for tightening and securing them to the roof rack. You can simply do it by hand, but the clamp has a ratchet mechanism, meaning you just turn it by hand until it reaches the maximum and it essentially locks in place, making a clicking sound like a ratchet, without the fear of overtightening and breaking it or not tightening it enough.
- Finally, the most important thing... it has locks on both sides, so depending on how you park, you can open it from whichever side is more convenient for you or depending on how things are positioned inside.

Negative points: maybe the only thing is that you can't install it by yourself, so you will need to consider that you will need someone to help you put it on the roof rack, but with 2 people, it's very easy... you can even have a child or your wife do it. If you are a bit stronger, you can do it by yourself, like the guy at the store who sold it to me.

And a piece of advice... if you only use it for 4-5 trips a year and not as a permanent fixture on the car, then don't get caught up in the extra liters and whether it's too much or not... if you're going on a trip, especially with children, the main goal is to be comfortable and not to be bothered and thinking about how to play Tetris to fit everything and have your wife complaining in the background, "What is he doing all this time?"... Above all, the job should be done smoothly :)

I had very good recommendations for this specific roof box and finally bought it. On the first trip I used it, the two shocks that hold the lid open broke. Big disappointment. First disappointment for a product that I considered immortal. The shocks were made of plastic and broke with little pressure! I contacted the store where I bought it and without much explanation they told me they would send me two new shocks for me to replace the broken ones. The next day I had them. I realized it was a common problem and they were expecting it at the store. The new shocks (easily replaceable) had an iron rod and they seem more sturdy. On the second trip, I saw that one of the pins on the hooks was starting to come off (it would come off when I applied a little pressure to close it, without pressure nothing was visible). I realized it is quite sensitive and does not require much resistance when closing the lid, compared to a Hermes roof box I had before the Modula, which endured much more wear and tear. Otherwise, it is quiet, it does not make a tremendous noise. CAUTION: You must place it in the middle of the roof because otherwise it increases the drag, as it destroys the car's aerodynamics (and increases consumption by 20%) and it is dangerous in turns (I traveled like this and the car was struggling and I was afraid of losing control!). When I installed it correctly, everything was fine. Also, it does indeed fit a lot of luggage (it is better to have them in duffel bags) and it can be loaded from both sides.