What brand are your boots? I learned the hard way that sometimes boots only fit well wth bindings of the same brand.
If they're ThirtyTwo, Vans, Nike or another boot-only brand, they'd fit with most bindings but would fit best with binding-specific brands such as Union.
Right now I have a pair of Ride boots and a pair of Union DLX bindings, and although they do fit, they don't fit well together. One of the reasons I'm getting a pair of ThirtyTwo boots is to solve this problem.
If you can't decide between 2 or more certain bindings, you should consider which will fit best with your boots, if you haven't already. That's usually a good deciding factor.