My introduction to Hellman's was around 1970/71 in Cleveland. Prior to that, I'd never paid any attention to whatever mayo we had growing up, but this college friend was making a few of us some good sandwiches and pointed it out, saying it was the only one to get. On moving to L.A. in 1972, I somehow accidentally bought Best, not even knowing it was the same, but it was, so I stayed with it. On moving back east in 1989, it was actually something of a thrill to be able to buy the Hellman's again because it's also just a great name. (Best, in contrast, sounds so generic.)
So would I try Duke's or some other regional favorite? Absolutely. I love trying out regional things, and I'll go with whatever I like. It's doubtful, though, that mayo is something I'd jump ship on. But I would also like to try some good homemade mayo sometime.