Though I like them all, I have to say my favorites are Sticky Fingers and Some Girls.
Lately, I've really been getting into the Stones--been wearing out Youtube watching all the videos. I like to do a before and after type of thing with Keith. If you check out Keith in 1974--he's a little scary--missing tooth and all. (see 1974 interview video). If you flash forward just four years to 1978, something happens--he's all healthy looking like he just got back from a surfing trip (i.e Miss You video). Flash forward three years from that point to 1981, (Worried About You video) and he's back to his,"Gentleman Corpse" look.
I find it interesting, but maybe I just have too much time on my hands.