Looking at the frames, I would say the Tern is the most rigid with it's full rear triangle and hydroformed front. So it gets the power down best and hence fastest. Tern also has nicer folding handles. If you ride in the rain or heavy traffic I would invest in disc brakes. Out alone in the dry on flat land...you'll survive with rim brakes. There's no doubt discs are better but the cost is up to you.