Tarkin and Ben fall into that weird category for me- their existing figures are good enough, especially the updated Ben that came in the cantina set, so I don't need a redo. Would I buy one if they did it? Yeah, probably, depending on how much of an upgrade they really are. But I'm also totally cool keeping them as-is if need be.
3P0, however, I think could only benefit from an upgrade. Having gone over Phasma with a chrome paint pen recently and loving the result, I went and got a gold one too to go over 3P0, but part of me is still holding out hope for a new one, especially now that we've gotten a more correctly sized R2. I doubt it would be super chrome-y, so I may still hold on to this one and fudge it into another part of the collection, but I digress.
ESB Lando is another one that could greatly benefit from an upgrade, but given how poorly all of his figures seem to sell, I can see them holding off.