The antenna "issue" was massively overblown, and later proven to be a non-event, with almost all phone susceptible to similar issues. I wouldn't worry about that in the least.

At this point, so close to the launch of the next generation, I would wait for the iPhone 5, or 4GS, whichever it is. If you can't wait then I would suggest the iPhone 4, as the older a phone gets the more likely it is to get left out of the next iOS upgrade.