I used to go by brands first, not much now. I am coming to the realization that if the oil meets the specs required in the manual than you are good to go. My cars spec API SL & SM grade oil. Since most current oils are SN or Dexos (even better), I figure that they are plenty good enough. With regular use, good quality filter, 5000 OCI change, and regular topping off if needed, it would be difficult to measure if one brand is marginally better than the other, the bottom line being they are all good 'enough'.
But the lure of the "best oil" is nonetheless quite enticing. The way look at it nowadays: look up the Lubrizol oil spec charts. Find the spec which is most demanding. For example you may choose MB 229.51 or another Euro spec. Find a oil brand in your required grade that meets that spec, and if the price point is acceptable, or even better the same as the rest, then use that one.
Right now, Walmart likely has all the Pennzoil Synthetics priced the same around $23, including the Euro with meets the MB229.51 spec I think. That might be one way to arrive at 'best oil' answer, at least in my mind.