July or so, go to Moana Surfrider. They have Mangoes at the Moana festival. They have a competition for best backyard mango. Mango entries supposedly come state wide. Attendees are privy to taste them for free.
Also, just go to various farms and see what get? Frankie's sells all kinds through the season. I"m sure if you go Kona or West Maui probably can find tons of various varieties.
Personally, I like Momi K, Maha Chanok, Kurashige, Fairchild Julie, Himayuddin. But that's just me and everyone is different so just gotta keep eating till you like something.