The thunder is supposed to have the best touch screen ever, and I've already heard great things about it already, but I'd still go with the bold. Even with touch screens that give you feedback when you press them, like witht he dare, they just aren't as easy to type with as a real tactile keyboard. I'm using a curve now, and even though the keys are pretty small, it still works really well and I can text and type pretty fast.
So I'd go with the bold. I love my blackberry, and I'm sure you will love yours too.