2nd threepeat team is probably culturally the one that will be better remembered, in part thanks to the presence of Rodman. Early 90s Bulls team probably faced better teams in in the playoffs and Finals.
LeBron could see this as his last crack at an MVP. If he has his usual season and the Cavs win 60 games, he will probably get a lot of buzz for the award while the GSW guys split their votes, but that all depends on whether or not the Cavs decide to go all out, or coast.
I just question whether Harden and YNB's teams will win enough games to get real consideration.