What if it's someone like Enterprise that's really the most customer focused, but without an earnings program or elite program? Would you still then care about who's got the best customer service?

People who rent locally seem to really like Enterprise (as I have when I've used them for replacements while my car was in the shop). But renting at random airports is totally different. I've never even tried Enterprise at airports, since Avis is good enough for me (though that's because I rarely need their customer service, which often isn't that great), and with Avis I can earn tons of airlines miles or hotel points through rich partner bonuses, and I care about that more than customer service. (And last I checked, I can't earn any airline miles or hotel points with Enterprise, let alone rich bonuses on same.)

But the lack of an elite program or an earnings program is not the same things as customer service.

(Nor is the lack of locations the same things as customer service. What if the best customer service is at someplace like Sixt that only operates overseas? How would that help you in the US?)