Hmmm....I found the Revell multi piece body kits I built as a kid in the '80s rather challenging ('59 Skyliner, '60 Corvette), but they did turn out pretty well. The first model I ever built way back in 1978 was a Revell '56 Chevy 2dr sedan w/ opening doors, trunk, etc..it was challenging (but I was 8 at the time).
For sheer lack of accuracy and badness though, it's hard to top the various Palmer kits I've inherited/etc over the years...
I found a lot of the '80s MPC reissues to be not so great...poor fitting, molded in hideous colors (bright orange, bright yellow, black, bright blue) w/ dark window tint, poor chrome, flash, etc. Years later I've aquired the original issue versions of many of those, much better.
I've also found the Trumpeter kits dissapointing for various body accuracy issues, at least when compared to vintage annuals of the same subject.