If you're just building consumer apps it doesn't matter. They all have debugging capabilities. The developer phone is mostly just beneficial if you're hacking on the OS since it isn't locked down by the carriers.
I've been using a G1 for months and had no problems. If you want the better camera and don't mind the lack of a keyboard then the Magic/Sapphire/myTouch/G2/whatever-they're-calling-it-now will be fine, they're otherwise identical.
