Sometimes "less" is more. ROTJ still manages to be better than at least 2 of the 3 PT films, and it's a toss-up comparing it to ROTS. On the other hand, ANH and TESB are hands-down better than all of them.
I'd give ROTJ the edge myself, just because it's fun and still has a bunch of characters we like and care about.
ROTS might be appropriately epic and have lots of cool-looking sequences, but I still find myself unable to really care about any of it.