Depends for me as well.
Air flow patterns being foremost. If air is going to blow the rain right up under my sleeve, the glove goes to the outside.
Gravity being second. If air doesn't matter, which ever way will have the water dripping out and not in. Ape hangers, glove out. Clip-ons, glove in.
And then there is the matter of gauntlet length, elastics, closures, etc.
But usually, when riding, it's glove out.