I tend to ignore the Elite Four as they don't have much in terms of personality or backstory, plus their role in the games is very small. They tend to be very forgettable.
I'd say the Kalos Elite Four are my favorite E4 as they have a beyond-awesome battle theme and Malva actually has (gasp!) a personality and does something in the game besides sitting in her room at the Pokémon League. So far, Malva is the least two-dimensional member of any Elite Four ever.
As for the rest of the Kalos E4, Drasna is fairly challenging and Wikstrom too put up a good fight. I was pleasantly surprised.
A honorable mention goes to the Kanto Elite Four. I respect the hell out of Agatha for curb-stomping me many, many, many times in the old days of R/B/Y.
Sad, but true. GF, themselves, mostly ignore the E4, so most fans do, too. So much for being the "strongest trainers in the land," huh? :rolleyes2:
Out of the games I've played (RBY, GSC, and RSE), I guess I have to go with Gen 1 Indigo (NOT "Kanto"... Kanto and Johto share the same League, so there's NO such thing as a "Kanto E4" or "Johto E4"!). They don't have the greatest teams, but Lance is awesome (and hot :P) as a character, and Lorelei and Agatha both have great potential as characters, even if GF never realized it (and have since mostly discarded them from canon). Bruno was the only real dud of the group.
Gen 2 Indigo was TERRIBLE. Bruno still sucked, Will was an insult, and Lance, bless him, was one of the most underwhelming Champions ever. Karen was the only good thing about this group.
As for Hoenn... Meh. They're pretty forgettable bunch. None of them even used unique types, and Glacia, in particular, had a
pathetic team. Drake will still always be the Orange Islands hunk with the Dragonite to me, not some old shirtless guy from Hoenn. :P