I know what you mean by it being S, but Gaki has always been a varied show so there's a little something for everyone. Aside from the specials, I've always enjoyed the "これやってみたかってん" and "この一口に命をかけろ" segments.
I try to catch Red Carpet and Red Theater every week, but it mostly depends on who's appearing. I missed last week's though, which I'm pretty bummed over since apparently Bakarhythmn finally got the Red Carpet award. Arabikidan is pretty fun at times as well.
As for favorites, I've got way too many... In terms of different aspects, though:
Manzai: Nakagawa-ke, Tutorial, Total Tenboss, Audrey
Skits: Nakagawa-ke, Monster Engine, Banana Man, Jarujaru
Variety: Cream Stew, Untouchable, Ninetynine, Neptune, Jichoukachou
Anyway, if people ask me about my absolute favorite, it's Nakagawa-ke.