I noticed on the previous page I said the Bentley handles like ass, but that was before SMS updated it. Now it's fantastic. It's no longer as fast in a straight line, but it has massive cornering grip. One of the best gripping GT3 cars.
For you guys that listed all of them, where do the Cadillac, new Merc AMG and Corvette fit in?
I would rank all the GT3 cars as follows:
Tier 1: Ruf RGT-8, Aston Martin V12 Vantage, Bentley Continental, BMW Z4
Tier 2: McLaren 12C, Audi R8 LMS Ultra, Mercedes-Benz SLS
Tier 3: Mercedes AMG GT, Cadillac ATS-V.R, Ginetta G55, Chevrolet Corvette C7.R, BMW M3 GT
Tier 4: Aston Martin V8 Vantage
For me, the Mercedes AMG GT could be in either Tier 2 or 3. Either at the tail end of Tier 2 or the front end of Tier 3, it's kind of in the middle. Though I've read people saying it's actually one of the fastest GT3 cars. I personally don't like the way it handles. It was by far the most difficult GT3 car to set up. My opinion is that aerodynamically it's too front-biased (lacks high speed stability), but the chassis is biased toward understeer. So it understeers at low speeds, but unstable at high speeds. So trying to make it more neutral at low speeds will make it even less stable at high speeds, but trying to make it more stable at high speeds will make it understeer more at low speeds. It took me a long time to get to a set up that made it feel ok.
I don't actually find the Cadillac to be that quick. Definitely quite a bit slower than the Bentley. I think that the Bentley is superior to the Cadillac in pretty much every way (speed, grip, handling), but I've also read people saying the exact opposite. The only thing I like more in the Cadillac is that it's left hand drive. It always takes me a bit of time to get used to the right hand drive in the Bentley on how the car is positioned on the track.
The Aston Martin GTE is truly in a league of its own... in slowness. In my testing (granted I really only tested on Spa), the difference in time between the fastest car in Tier 1 and the slowest car in Tier 3 is smaller than the time difference between the slowest car in Tier 3 and the Aston Martin GTE. I also recall that the Aston Martin GTE even uses slightly more fuel than the Aston Martin GT3. But I think the GTE might be better on tire wear.
In the end, other than the Aston Martin GTE, it can really just come down to personal preference. Like which car's handling you like most, or which one you can be most consistent with. Because even in my testing on a long lap like Spa, the difference between the fastest car in Tier 1 and the slowest car in Tier 3 was only 1.117s. If you have different handling preferences than me, the order of those could probably easily shuffle around.
My own personal favorite is the Ruf. I'm quickest on Spa out of all the GT3 cars in it, and it's my favorite in terms of handling. I don't think it's more difficult to drive than any of the other GT3 cars. Its handling definitely feels unique compared to the others, but I like it for some reason. I think it's really stable.