Well if NFA lowers are verboten for the purposes of this thread, I’d go with Noveske, Mega, then I guess try out one of the ambi-coolieo SR15s.
But honestly I don’t get too stuck on lowers - I started with Mega Machine lowers for my first build about 10 years ago and aside from getting a Noveske lower to match an upper, that’s really all I use - markings really don’t mattter but I just defaulted to Mega.
I know it’s boring. ;)

