I love Ruger 10/22 - especially the Takedown. My only real complaint is that it can be a bit finnicky with ammo at times - I've had a couple of failures to feed on a MX-25 (banana clip with 25 rounds in it). But for training/practicing there isn't anything better.

If you're looking to expand into pistols, I'm a huge fan of starting with an SR-22 from Ruger - the 'manual of arms' (i.e. buttons and switches) is very similar to a 'real' pistol, it eats pretty much any .22 round, and you can dry fire it as well, which not all .22s will do. An excellent way to 'learn' a pistol until you're ready to move up to a larger caliber, whether 9 mm, .40, or .45.

As an aside - to echo what others are telling you, I would learn to shoot your irons first. I started with an AK (despite military experience in AR-15) and unless you're consistently scoring hits from >300 feet with irons, you are the limiting factor, not your rifle/iron sights/scope/round. I have taken a couple of classes, both rifle and pistol, and those (despite the sometimes crazy right-wing rhetoric thrown in) have been quite helpful.