Alex,
If you have a particular application and type of engine (gas/diesel) in mind, I can tell you the best product from each of these manufacturers for that specific application. But to talk about a best oil without getting into more specifics makes no sense. My recommendation would depend on how much oil you are burning, the number of miles on the engine, and the length of the change intervals you plan to run.
For example, if you plan on changing oil every 3000-5000 miles, I'd generally recommend Mobil 1, 5w-30 or 10w-30, unless you were seeing significant oil consumption. If you want to run 12,000-15,000 mile change intervals, then something like the Amsoil Series 2000, 0w-30 would work better. If you were looking for a 40wt oil, this new Redline 5w-40 has been putting up some very good numbers.
The question is too general to give a good answer ....
TooSlick
Dixie Synthetics