i have a size 10.5 boot. should i go with...
i have a size 10.5 boot. should i go with a medium or a large?
you could fit in a medium, but I would go with a large.
Large fits 10+
FWIW, I wear an 11 and I've got the toe cap-strap set on the second-to-last hole, and have to really crank it almost all the way down. Not sure what this means for you b/c all boots are going to fit a little bit differently.
I'd recommend taking your boots and fitting them in to the bindings at your local snow shop.
I wear a large with a size 10 Hail.