Vladimir. I main Vladimir and this is probably biased but i think he has best survivability for being a carry. He also contributes to teamfights exceptionally well with his ultimate and tides of blood. He can focus one person with his transfusion, all while healing himself.
If you get focused while in teamfight just use his pool. 90% of the time people will forget about you and focus someone else. I would first try to kite and use pool if you think you will die. I always have flash if things get too bad. He also is pretty beefy because ability power gives him health. Most important for Vladimir is Magic Penetration, specifically Void Staff.
And here's a trick: If you know a teamfight is about to happen get Tides of Blood to full stacks. That way you will deal 200% damage with it.