In theory, and the EU, they can be interesting. They're outside the law and all have specialized skills, plus they're aliens (most of 'em).
But I'm not one of those going for ALL the bounty hunters.
In the movie, none of them except Boba Fett does anything. There are a lot more characters, including other aliens, that actually DO something or if you forego some of the hunters, you're left with other figures that can set the stage for other SW environments.
Now some people's favorite thing are the bounty hunters. And that's cool.
I voted for IG-88 besides Fett. IG is a Droid and so few of them are making our list (the Gonk Power Droid is on my shortlist for the "environment figure" as it fits in everywhere - but IG-88 is more interesting as a hunter). And Boba Fett does need competition, and it looks like he had to fight IG-88 off-camera during ESB, because IG's parts are in the Bespin smelting room when Chewie rescues Threepio. On top of that, Mandalorian-armored Clones versus the war droids is central to the prequel trilogy, and there's not too much difference between IG-88 and IG-86.
Now if Bossk hadn't already made the list from a lot of other people's votes, I might have prioritized him over the Ugnaught - but I like the idea of wild variances in shape and sizes of my SW characters. (Too bad Jabba The Hutt doesn't qualify as a "figure" for this poll). Anyway, the Ugnaught sets the stage for Bespin like the aliens for the cantina and the Ewoks for Endor, the Jawas (and Tuskens) for Tatooine and the skiff guards for Jabba's. That's the same thing like the Gungans, Podracers, Senators, Kaminoans, Geonosians, Utai, P'auns, Polis Massi, Mustafarians, and the miners. Kind of have to have them to recreate play where your intention is for the action to take place.
Anyway, after all my explaining and dialogue, I'll repost my list so it's clear:
1) TIE Pilot
2) Luke X-wing
3) Grand Moff Tarkin
4) Ponda Baba
6) Death Star Trooper
7) General Veers
9) Endor Rebel Solider
12) Leia Endor