Whatever you get: in my opinion make sure it is adjustable focus. I don't know if I'll ever have another scope without it, but especially a scope that I may shoot at closer range. Even the rimfires that are parallax adjusted to 50 yards are not as easy on my eyes as ones I can truly focus at the exact distance I would like. Being perfectly focused just makes shooting more fun.

If you don't get adjustable focus, at least make sure it's a rimfire that's parallax free at 50 yards. Unless this is something you know you will exclusively shoot at 100 yards+.