Armalite, Bushy, DPMS, RRA, CMT/Stag, LCW, Superior, Mega - all are known good and will do just fine. I've seen a few QA issues with Olympia (not quite drilled/milled to spec), but there are also those that swear by them rather than at them, so who am I to say? There are a few guys I know that have Doublestar, Ameetec, and LAR/Grizzly lowers and they are happy with them as well. I'm partial to LCW (Lauer Custom Weaponry) lowers at the moment, since I've been doing a bunch of different caliber builds and the LCWs are not explicitly caliber marked....
If you think that you'll get rid of the rifle someday, I'd suggest using a lower from a rifle manufacturer (Armalite, Bushy, DPMS, RRA) rather than a parts manufacturer. You'll likely have an easier time selling the rifle if you do than if you used a lower from, say, Doublestar or Mega. It's not as if a lower from a parts-only kinda outfit isn't as good as one made by a well-known AR manufactuer; it's just that parts-only manufacturers such as Mega or LCW or DS have brand names that are only really known within the AR community and not within the broader spectrum of gun buyers at large.