I've heard different schools of thought on HT versus FS bikes for beginners. Some believe that if yoiu learn on an HT, you'll develop better habits in terms of clearing obstacles and picking a good line. Others believe you should use a FS if it'll make riding more enjoyable and/or if the trails in your area necessitate it.

I learned only briefly on an HT before getting a FS bike. I'm sort of the of the mind that the best way to learn good technique is to take at least one comprehensive skills clinic and practice, practice, practice. Riding a HT doesn't, in and of itself, teach you good skills. Similarly, riding a FS doesn't necessarily mean that you don't have good skills. In the end, I think it's far more important to get a bike that really fits, regardless of the type of bike. Ideally, it'll be one with components good enough that they won't leave you frustrated on the trail. I had trouble shifting on my HT, which has lesser components than my FS (I have a Santa Cruz Juliana). But both bikes fit me though and I arguably could have continued to ride on the HT. It's just that my bike lust won out.

If you're in a position to test ride (on trails) a bunch of bikes, do that. But keep in mind that it takes a little work to get a FS dialed in all the way, so it can be hard to judge. Hopefully though you'll at least get a feel for how each bike handles and whether it fits. When you test ride a bike, make sure that you get out of the saddle and actually move around the bike in the way that you'll actually ride it. Don't just sit and pedal.