To use efficiently ay you need to be midnight blade, while crimson fist can still let you use him better than other mains won't give him what he needs to shine.

On the other hand the only lineup that let you use efficiently the 30 chase of roshi with earth main requires dbp hidan and king of hell, two requirements quite hard to meet for a f2p.

So you can try or the full shield immortal lineup with gakido/bee sst and gaara kk (or hashirama if you get lucky in dropping him from a pack) that can't care less about the 30 chase or the less optimal solution for the 30 chase with yagura and bee sst or utakata.

If you want to stay cf, anyways, roshi is better since your shields will let him survive and stack up defense and ninjutsu, that's the real op passive he owns. The 30 chase is not that important since as cf you put him in front row and you spread ignition by letting him be hit.