You want a Mil Spec lower ... most if not all will be. For a lefty configuration it will be the upper that is different. STAG makes lefty uppers and I think a couple of others just not sure of the names.
When it comes to the lower it will be personal preference really - rollmark, forged vs billet, finish quality, etc.
Member: NRA GOA
Est sularas oth mithas
"either way, you were guilty by association, so you were smited...." JD