First Blood is a very special movie, since it started it all.
It is also less Hollywood than the others.
I do have great memories of Rambo 2 though, since he introduced his glass-fiber bow with arrows with explosive tip.
And he also showed us a whole new type of physique, i don't think we had seen anyone so ripped before that.
First Blood 1 and Rocky 1 didn't inspire anyone to work out (since the physiques weren't as impressive), but Rambo 2 and Rocky 3 did inspire us for sure, as did Conan.