Since my renewed interest in ARs kicked in a while back, I've found that I really like ARs in the form of SBRs/Pistols. They are really handy. I am a smaller guy so for me, they just plain make sense.
In the past few months, I've built a 10.5", which is soon going to be an 11.3" in 5.56. I followed that up with a dedicated .22 build. I went the whole route. Dedicated upper and a dedicated lower with last round bolt hold open. No kidding, as of this past weekend, I have something between 13 and 15K rounds through that thing. Been through two firing pin springs. A firing pin. An extractor, and extractor spring. Cracked a bolt frame (which CMMG replaced quick as lightning), and every time I shoot it, I think "I should have built one of these YEARS ago." I shoot that thing so much that the cost of .22 ammo is becoming something more than just a negligible expense. The little 9" CMMG barrel is very accurate too. I've never shot it for groups, but hitting golf balls at 100 yards is very easy to do.
I have two builds in the works right now. I'm sticking the the shorter barrels and rounds that do well in shorter barrels. I ordered a 350 legend barrel that has just been sitting there. I think the fire for the will burn hotter when I am geared up to load the ammo for it. I'm still on the fence on a few things too. Like red dot or LPVO and whether to do a whole build or just an upper.
I did order all of the parts for a 9mm build also. Those will be in this week...I hope. I went with an Aero upper that does have the dust cover, but does not have a forward assist, since I'll be using a Faxon BCG that has no provisions for a FA. The barrel is going to be a 5.5" Ballistic Advantage. For now, I'm going to be using a lower that I have laying around until I decide to go Colt or Glock pattern magazines, although I'm leaning toward Colt right now. I'll be uisng Mean Endo mag conversions in the mean time.
Once I finish the 9mm, the 350 legend is gonna get built. I'm in south Louisiana and even when hunting, shooting past 200 yards is rare. I'm sticking to up close stuff.
Just whatever you do decide on, pick something with a good availability for magazines and commercial ammo. It's always good to be able to find ammo in a pinch. They sell 350 Legend at Academy for $.50 a round.