I am a fan of the 25th Anniversary, for whatever odd reasons I've got. I can understand why people would prefer the return of the o-rings. The Anniversary line has allowed me to get back into the hobby without totally going bankrupt; I can now build my coveted Cobra Army.
I really do like the o-ring Cobra Officer...if only because it's "me" in Troops of Doom. I got to kick Boba Fett in the nards!