Getting back into sim racing this year, I wasn't sure which game I was going to settle with, as there were plenty to choose from. Between AMS2, ACC, and rFactor 2 (I've done iRacing before, but I didn't want to go back to it), I didn't expect AMS2 to come out on top, but in my opinion it's the best of the lot.

Where AMS2 is good:
Physics - I know this is highly contested among sim racers, but I much prefer the feel of AMS2. Perhaps it's in the way that you can feel the car grip in compression, or start to loose it when pushing the limits of the tires, I can very easily feel the car and know what it's doing at all times. In that regard, it most resembles an older sim I first learned car control and physics in, Live for Speed, where the tire and suspension flex and the contact patch on the road all come together to give a very good driving feel.
Content - I've been racing different cars and tracks multiple times every week in leagues, and still haven't driven most of what's available. The variety is awesome! Of course I wish some more of the Project Cars 2 tracks were in the game, but with some modding tools released recently, this might be coming soon.
Weather - Driving in the rain is something else, it's terrifying, and really teaches you to take alternate lines in order to be faster.

Where AMS2 still needs to improve:
Multiplayer - Large lobbies having multiple drivers getting disconnected when switching sessions, and sync issues causing drivers to have different conditions on the track from other drivers makes multiplayer the biggest weakness of AMS2. I even had one race recently where the lead driver crossed the finish line very close to when the race timer finished, so half of the field saw him as completing the race, while the other half didn't and had to do another lap. This caused several of the former drivers to be overtaken by the latter drivers. These flaws with the P2P system are a shame, as otherwise it's very convenient and makes it incredibly easy to host lobbies. There should also be some more server controls to make hosting league races easier, and I dislike that passwords are visible when joining a password protected lobby, not very good for streamers.