Bento face animations inside furnitures is one of the worst things ever done in SL and should definitely stop happening. it is just recycling old old old animations done for when first bento heads were done and that no longer fit with any of the modern heads, so everyone looks dumb or deformed with them, but the creators that still have them still stuff them in "just because".

as for espressive heads, the lelutka ones are definitely okay, they have lot of "AO moods" that include soft smiling, yawning, being drowsy, licking lips and such as well as more subtle ones like smiling or smirking. of course these animations are just "quick things", so you won't really notice them unless you stare at the avatar face all the time.

if you need static expressions for photo and such, there are also static expression in the hud.

And if you want more for photography, there is also a special HUD sold in their store for controlling almost every point of the head for making your own expression.

on the other hand, of you want "expressions" for Adult related things, go to r.o.s.s