There are only a few oil manufacturers in existence. The difference between the brands is the additive packages. Just stick to a high volume popular brand and grab whatever is on sale, you will be fine. I typically run Penzoil or Valvoline but most are just as good.
Interesting comment re oil manufacturers and additive packs. I've heard something similar to that a few times, but never anything conclusive. Any info on which brands are rebrands, what the differences are between additive packs and what advantage/disadvantage there are to them?
When it comes to Dino oil, I am in the Castrol GTX camp but I have used Valvoline also. I am pretty much a synthetic user now due to short trips and high ambient temperature. Even in Synthetic I most often get the Castrol Edge.