I'd like to see X-Files done again to modern sculpting standards, Frank Black from Millennium too. With the show resurrected might be in with a shot at someone doing the former, even if it's of older versions of the characters, rather than how they looked back in the day. The latter, not so much.
I'd also love Blake's 7 (at the very least Avon and Blake), Number Six from The Prisoner, and the Red Dwarf crew, but I don't have high hopes. Someone like Big Chief is free to come along and surprise me, though, if they like.
Quality original series Star Trek figures are surely only a matter of time, someone has to nail those down eventually. And when they do, I'll be there with cash in hand.
From the land of it'll never, ever happen, I'd take a Kolchak from the original Night Stalker series, Titus Pullo and Lucius Vorenus from Rome, Al Swearengen and Seth Bullock from Deadwood, and a whole bunch of characters (Spartacus, Crixus, Oenomaus, Ashur, Gannicus...) from Spartacus. Be highly tempted by some Black Sails figures of the main pirates - Flint, Charles Vain, Jack Rackham, Ann Bobby (and potentially next season's Blackbeard) too.
I'd also grab a quality Xena, as someone mentioned earlier, maybe a matching Callisto as well, though I have no interest in any of the other characters. Possibly some of the key characters from Farscape and Babylon 5 if they really nailed the likenesses and designs.
So yeah, there's a lot I'd buy. And that's just off the top of my head. Unfortunately my tastes tend to lean more towards the kind of niche shows that rarely see high end collectibles made of them, let alone good ones, so...