If you throw out a couple of scam artist oils, all of the rest are pretty similar. For some unknown reason, I still feel that Mobil 1 is one of the best out there, but have absolutely no evidence to back it up. On my tractors, that have hydrostats that take some work to change, I only trust them to Mobil 1 15w50. Aside from that, I use ST, Mag1, AZ, Oreilly's, AA, RK, Traveller's plus all the major brands, pretty much interchangably. I just don't see any major differences in brand. I do tend to stick w/ syn in all three cars, not based on any need, but that it's usually only a few dollars more than conventional.
Just to show I'm serious, my 2008 PT Cruiser has 5w30 Quaker State Ultimate Durability in it now, my 2013 Altima has RK 0w20 syn ($2.59@qt, hard to beat), and my 2010 Tacoma has Pennzoil Platinum PurePlus 5w20.