One of Monreal, Felipe or cissokho i.e only if Abidal is no longer with us. Even at 31, he has a great engine and can outpace the aforementioned players. He still has a good few years left in him.
I'm happy with Abi and Maxell House quite honestly. But if we did move for someone I'd like to see either Felipe or Coentrao. Either would be a lot cheaper than someone like Evra or Clichy (awful last season).