If you're concerned about the amount of kick you could start with something small caliber like a .22 and work your way up towards 9mm, .357, .44 and .45. Caliber isn't the only thing that determines kick but it's a good place to start.
Shooting a shotgun is a lot of fun because it's easy to hit your target. Birdshot has a low kick compared to buckshot.
I don't have much experience with rifles but they'd probably be a lot of fun to shoot too.