Tye,
On this forum, expect the answer to be the Sportster!
And based on your stated pupose, I'd recommend the Sportster anyway. My kids and I shoot Sportsters with Super Colibri (red box) ammo. We often shoot at a friend's house on the edge of town. This ammo has no powder, the bullet is propelled by a primer mix only.
They are very quiet (make less noise out of the Sportster barrel than my wife's pellet pistol makes!) By the way, don't use the blue/yellow box stuff in a rifle barrel, I've had the bullets stick in the barrel because they don't have quite enough ooomph to make it all the way through. Okay for handguns, but not rifles.
We also shoot regular .22 of course, and the Sportsters are quite adequately accurate with even the cheapo stuff.
I can't say anything about the Marlin, since I have never had one, but I do recommend the Sportster for just plain fun. It is lightweight, accurate and inexpensive... I just bought one at Walmart for my wife last week, list price was $108.00.
Hope this helps.
Cheers
Kerry