Big Red, based on VOAs and UOAs some of the best looking conventional motor oils appear to be Pennzoil, Castrol, and Chevron Supreme. Now, not all different brands of conventional motor oil have been tested by memebers of this forum, but of those oils that have been tested, the three oils listed above appear to be very good.
There has, in addition to the VOAs and UOAs, been some limited amount of freezer testing of some motor oils. Pennzoil and Castrol seemed to flow well at pretty low temperatures. But the Chevron Supreme, according to information supplied by the tester, do not flow well in extreme cold. So maybe it is not a good choice in the wintertime if you live someplace where it is cold.
As far as I have been able to determine, based on the VOAs and UOAs that I have seen, Pennzoil and Castrol would be hard to beat as conventional motor oils.