Zeewolf 1 and 2 are definitely a lot smoother on an A1200 with fast RAM or accelerator.
Stuntcar Racer is smoother
UFO Enemy Unknown is a much better experience with an 030+
The unofficial AGA port of CD32 Wing Commander is nice to, and has nice 256 colour graphics whereas they're 32 colour on the A500 version.
Carrier Command is a bit smoother, but it was pretty smooth already.
If anything, Syndicate is way too fast on anything over an 030, and actually needs slowing down to be playable!
F1GP is improved, BUT you need to patch it to unlock the framerate. It crashes if you specify anything over 25fps though.