I have a few. My favorite is my .308 Ruger Scout rifle. I also have a 9mm pistol and 5.56 rifle (not an AR type) that I can't get ammo for anymore but used to like shooting.
I didn't to with an AR platform because there's such a thing as too much choice in a market. It was like trying to build a PC- every single part had 30 different options for style or manufacturer and they all had conflicting reviews on quality, which made it seem like kind of a gamble no matter what I did. So I just went with a different pre-built rifle and avoided it entirely.
You can't find 5.56 ammo? Dang, I'm almost swimming in it. Lol