I'd go for the allez if I were you. Single speed = one trick pony imo, some people like them but personally I think it's safer for your knees to have some lower gears. They're ok if you've got good leg muscles but until you have you're just wasting cartilage!
Only go single speed if your planning to go off road... that's the only time gears tend to break.
They're a pain when they are new due to the cable stretching, but this is so very easy to fix and a bike shop should put it right for next to nothing, if not nothing (if they're an honest bike shop)
Or, there are plenty of "how to's" on the web, just look for re-aligning rear gear mehcs