I had the same dilemma a few days ago and solved it by going into some shops to look at them.
My first choice was the Vega, before I'd even heard of the Hannspad. As soon as i saw it though, I was disappointed. It has a massive ugly bezel, and the screen is seriously dull, lacking in brightness/contrast.
After that experience in PC world i didn't have much hope for the Hannspad (in carphone warehouse), but i was pleasantly surprised. The Hannspad is almost all screen, as a tablet should be, and the screen itself is quite bright. Still not iPad or Tab quality, but good enough - similar to a good netbook screen. It didn't handle the very bright lights of the shop very well, and the viewing angle from below wasn't great, but i only noticed this because I'd heard people complain - can't see why it would be an issue in real world use. This was the '33 model - the '53 is supposedly better, but I thought the screen was fine.
It also just FEELS like a higher quality product, unlike the vega.
Re: USB drives - i think this is still on the to do list for the ROM devs.
Ebuyer have now split their stock and have separate entries for the different models - so hopefully the one that's out for delivery to me today is a '53!
Hope that helps...