Purely f2p, Sasuke/Kimimaro/Jugo root team but a lot of f2p can get cheap old rares like Iruka/WB Asuma, so Kimimaro/Sasuke/Iruka root team and Iruka/WB Asuma/Guy light armor team are the best 2 teams without any Kage rares i would say.

They both show up in events, Iruka is about 700-900 coupons for 2 star and Asuma is like 2k-2.5k for 3 star depending on event and yeh they are both worth it, they help a ton on ninja exams and they give you a lot of exp/money long term on 9 tails.