There is no cut and dried answer to this question. You won't find any comprehensive guide for pricing errors. It all boils down to what someone is willing to pay. Chris
So you're a flipper and not a collector. IMO, the best ones are the ones you like. I agree with Chris. There is no pricing/value guide for them.
I like the 1909-S over horizontal S not a whole lot of coins where somebody stamped the MM in the wrong orientation. I also like strong separation between the MM's.
There are countless numbers of RPM's, and you can find them for just about every denomination prior to the '90's. I like this '36D Buffalo because I found it in circulation. Chris
Can I add to this and say that the "Best one's" are those that are the most "obvious" combined with the fact that you obtained it at face value. After that, all bets are off since it can be a fairly thin market.