GOMU GOMU NO... JET BAZOOKA!
[it's obvious, isn't it?]
EDIT: In a match against both of them Luffy might win if he used Gear 3, but Ichigo might be quick enough with Tensa Zangetsu, so it could go either way, but I'm leaning more towards Luffy, he's much stronger than Ichigo i.e. their bodies.