Guru3d and HardOCP are recommending just FXAA for Ultra graphics. I would start there and then experiment with adding MSAA, but I think you'll just want to stick with FXAA in the end.
I would suggest waiting for them to actually optimise that game properly; if you watch TotalBiscuit's video, "WTF Is... Watch Dogs", you'll hear his performance with his setup - and it will disappoint you, haha.