Tough one for me.
Liked them both a lot at times, but then there were times I felt that they were clearly overrated. Both were revolutionary in their own ways, but then became overrated because of their past breakthroughs.
Beasties were much more versatile, but I'm not sure I care if a group was able to make a song like 'Girls' or 'You Gotta Fight for Your Right To Party.'
If I had to go with one, probably the Beasties.
For starters, I had more better memories of Beasties songs. While something like 'You Gotta Fight' isn't what I would call the zenith of rap songs, it was a catchy tune that I remember back when I was 8 years old being wildly popular and having the time of my life listening to it while we were in a dorm room playing nerf basketball at the Jim Boeheim basketball camp.
Probably what gets me a bit was their extreme use of sampling which came off as beautifully innovative and turned into no talents like P. Diddy making a music career for themselves. I love 90's music, but the last couple of years of the 90's was really hard to listen to with the sample and copy+paste lyrics with hacks like Diddy, Will Smith, etc and forcing more talented rappers like Nas to follow suit or they wouldn't generate any interest. But, I can't blame the Beasties for that.
Probably what hurt the Wu Tang for me is that they just couldn't quite 'keep the band together.' GZA would also have some beautiful instrumentals, but often times the songs were way too short something that well done. I'm a fan of 'less is more', but in this case, 'less is less.' The problems with O.D.B. hurt as well as he brought something to the table that was noticeably missing when he was away.
I'd say that those great, truly deep songs....belonged to Wu Tang. I mean, tough to compete with something like C.R.E.A.M., something that anybody with an open mind could relate to, regardless of race. But if I wanted more catchy tunes, I'd go with the Beasties.
YR