Asari Valkyrie sentinel
I've said it before, but... I love this girl. She's ever so much fun to play. Risky, yes. But she totally wrecks everything in her way, while looking stylish and sexy and, if played properly, dying very rarely. Just don't dishonor her by giving her a wuss weapon like Hurricane or anything like that. Shotgun is the way to go with.
Easily my favourite kit in the game, bar none.
Asari Huntress infiltrator
Compared to her sentinel sister, she's an easy mode. She doesn't have to worry about cooldown because of TC and due to combination of DC and being able to carry any weapon at all, she's deadly at any distance. In my eyes, Claymore is the only weapon for her... if only because her natural sexiness is enhanced tenfold by it. She is my go-to kit when I suspect pugs will need carrying.
I like her a lot.
Paladin
An odd choice perhaps. Like any N7 character, he makes no sense whatsoever. Despite that, I really like him. Being able to do any tech combo in combination with omni shield is a great value and much fun to play. He can be an offensive or defensive powerhouse and I always love playing him. Especially against geth, since he literally destroys them.
Plus that sexy chainsmoker voice 