My votes go for the ferret, ghul, and anhkheg, in that order.

Given the occasional requests for a ferret figure, the surprising popularity of DAZ's House Mouse, and the rising trend in cuteness, I'd expect it to sell extremely well out of the gate.

We can always use more skinny-freak characters: rotting zombies, githyanki, space vampires, dark elves, Nehwon ghouls (from Fritz Leiber's Lankhmar), etc. Variety is good, and the existing Poser skeletons don't particularly conform well to any other figures without a lot of work.

And the ankheg ... well, I'd just like to see something that nasty in Poser. caleb68's spider drone comes close, but the head isn't insectile enough.

From a commercial standpoint, I might suggest that you consider working on a monkey, rather than a baboon. Monkeys have been heavily requested, whereas over the past few years the number of requests for a baboon figure can practically be counted on the fingers of one foot.

Say what you like about 3rd Edition (I can understand the reactions of the old-schoolers), but at least they finally pumped up the dragons with some respectable stats.