I own a Bushmaster DCM competition AR-15 (heavy-weighted national match version with match barrel, adjustable rear apertures, two stage trigger, etc). It's been a great rifle, and other than the two stage trigger being a little sticky at times, I've never had a malfunction with it. Accuracy-wise, I used to routinely blow the spindle out of the spotter plug at 200 yds out of the box with el-cheapo Sellier & Belloit green box ammo with the factory sites. All around great rifle, and if you buy a flat-topped version with a free floating barrel, it's almost limitless the amount of crap you can pile on one!
If you're new-new to shooting, I would also recommend something like a Ruger Mark III pistol. I have one with a bull barrel and adjustable match sites, and it's an awesome shooting little .22. Easy to service, aftermarket parts galore, and fits you like a 1911. Cheap as dirt to shoot, too!