Eh, I voted teleportation, for the simple cool factor, and not having to have a fucking pain in the ass car to go eveywhere would be really awesome. If it ever happens to be possible, though, I don't expect anything biological to actually be able to teleport and end up not dead at the other end. However, I would definitely not get tired of being able to teleport anywhere in the world whenever I wanted if this actually became possible. I guess a time machine would be even more awesome but to apply the real world a bit, I think it's been pretty much proven that you can only travel into the future (by going really, really fast), never back, which seems like a bad idea when you have no idea what lies ahead.
Youth elixir sounds great and all in theory, and I don't mean to imply that I'm eager to be dead any time soon, but, honestly, I'm not so sure I would want to be immortal. I mean, I guess I could still get run over by a bus and die that way, and I really wouldn't mind aging a lot slower, but....I don't know.