I have a dilemma, in that I just don't know which way to go in terms of sippy cups...straw or spout?

Straw cups seem to be very popular. But then with a spout cup, I would have thought the action of tipping it up would make it easier to transition to a cup later on?

DS can drink from both, but just not sure which to use for when we move away from teats for his milk...what does everyone else use?