Under the current situation best answer might be ...buy the one you can find....

I don't know who of these make pistols but I can tell you that the best manufacturers of mass produced AR15's are Rock River, Stag Arms, Del-Ton, Colt, and Bushmaster. Bushmaster is going downhill since the Remington buyout but their quality still seems to be holding on even though their business practices are falling apart. Del-Ton is new and up and coming but very good. Stag is strong and steady. Colt is old and true to their roots. Rock River is well established and solid.

I can't say that I have ever heard of KelTec in a rifle form but then again if they specialize in pistols, that would be why.

I have been in the business for 17 years. I do not work on pistols though, just rifles. We don't mass produce at my shop. We build custom competition and hunting rifles.