It all depends what angle you have your butterfly at. Some bags sit pretty high and may foul your bars, and dont offer much space to manouvre, ie angled down they hit the headtube/cables.
Look for a bag which has the quick connect placed high up on the bag rather than in the middle. I had the same problem a few years ago and found a Karrimor that had a couple of arms that the bag was suspended from and this was perfect. Not sure if they are still available though.
I think the best thing would be to try a few out at the retailer if possible.