All OTR microwaves are super noisy. There is no point comparing noise ratings for them, which is why you are not finding any comparisons. I am sorry to say that they will all sound like jet engines in your kitchen. They just are not designed to be quiet. They are designed to be microwaves that have an extra feature of an exhaust. The exhaust area is very narrow, which increases noise. You would do best to choose your OTR MW for other features, and capacity, appearance and price. Almost all MW's are made by Panasonic and Sharp, with many brands just being rebadges of those two. So don't buy e.g. a Viking or Dacor OTR MW thinking you'll have a better machine--they'll cost double what the Sharp would cost which is the same machine.

Most OTR MW's have 300 cfms. The Panasonics are more attractive, if that matters. However, I learned on this forum that Samsung has a new line of OTR MW's that have 400 cfms. I don't anything about them, but it may be worth checking out as there are no other OTR MW's I know of that have 400 cfms. However, I'd expect the 400 cfms to be even noisier than the standard 300 cfms.

We purchased an OTR Panasonic Inverter. It has 400 cfms. I really like it. Firstly no big handle sticking out. Push button.

I don't find it any louder than others and don't actually notice the noise. Doesn't sound like a jet engine. The fan starts as soon as you turn it on and shuts off when done. Bought it from Sears and have had it 3 months. So far so good.

Good luck!

I think the noise reference was for the hood fan, not the general use. I find the hood fans very noisy, and avoid using it above 'low' setting unless absolutely required.