Update! After more than 350 hours of gameplay, I already have 9 Warframes available to use. I've maxed ranked 4 of them already (2 of them thrice, and 1 twice). I have 2 Prime Warframes already.
My most used frame currently, is Loki. I'm going to forma (reset rank) him again if I'd be able to max rank him (lvl 30):
Thanks!