Agreeing with
@Movielover here. Try orange. As someone with a erratic stomach, I've never had any issues with it. Worse aftereffect I've had was my legs feeling "weightless" for about 15 minutes after it. And if you're worried about getting sick, don't look away from the screens. On top of that, the forces are only for short spurts too. Maybe 10 seconds tops for each (launch, slingshot, re-entry to Mars)? I could never imagine doing the ride with out the forces. I said before, that's its' "party trick". Without those, it's a less exciting Star Tours.
EDIT: To add to all of this, I think people are scared of orange because of all the warnings and the 2 deaths. I had a friend scared of orange and when it was over, he said "That was it? The forces weren't as bad as the signs make them out to be".