I would have to say that ROTS is definitely not the most watchable prequel IMO. TPM at least looks nice 1/3 of the time. Also, I can ignore Jar Jar’s antics to an extent, what I can’t is the ever present dialogue, the ever present ugly environments, and of course, “NOOOOOOOOOOOOOO”.
I think TPM feels and looks the most like Star Wars but ROTS has a few scenes that are really well done, John Williams’ score is also much better in ROTS