Kamina ~ Well, he was the guy who started the Gurren Brigade, and the very legend of hotblooded~ness who made Simon who he is and who he'll become soon.
Simon ~ Kamina's successor, and pretty much the future GARlock thanks to him. Plus, although he needs to be more cocky soon enough, he has a nice heart ad he's pretty GARhimself but it'll be soon when he gets to Kamina's elite level of GARness.
Yoko ~ Nice figure (Especially in time skip) + Badass attitude + BIG GUNS = Maximum Pwnage.
Darry ~ She's just too moe in the time skip and she's become a rather skilled pilot
Viral ~ Kamina's rival and now in a way, Simon's, or a possible comrade. Either way, he's still one of the most badass I seen.
Kittan ~ I always found him tough, daring, and ready for action. And ep 20 just hit the nail in the seal with that fact for him IMO.
Genome ~ Gotta admit, burning cranium, maximum pwnsome abs, that guy had to be one of the most GAR villains in the series