I play pretty much nothing but fretless. Everyone else has covered Zon and Pedulla. I think at least one of those guys is going to be hanging it up soon, if not both, which is a damn shame. GREAT basses. My #1 is a Steinberger, but they've been gone for almost 25 years now.
Kiesel make a good one, and the only 19mm spaced 5-string fretless I've found, so I might be getting one of those in the future. They're just a few miles from where I live. Status Graphite makes a tremendous fretless. Ernie Ball MusicMan, of course. The Fender Tony Franklin is a beast. And if any or all of these are too pricey for your tastes, Ibanez makes great fretlesses. The real sleeper is what I use for gigs (I don't take out the Steinberger these days!); the Cort B4FL. You can get one for under $600 and they're just great.
If you're dead broke, go find an older Squier fretless with the ebonol fingerboard. I see them for about $199 all the time and it's a perfectly giggable bass that looks great and sounds fine.