Is rammus a viable champion?

In ranked, the only champ that i jungle with is Rammus, i love playing him, i think hes a really fun champ and his kit is pretty cool. I feel like his ganks are strong with his taunt. But after playing him for a while i feel like he doesn't have a "strong pressence" in teamfights like amumu or sej would. yea, individual lane ganks are always good but in teamfights, he only has solo cc (his taunt). In the end my question is whether i should keep playing a champ i enjoy playing or give him up for a stronger jungler like sej that i dont enjoy? i dont want to give up rammus, but for climbing ranks, does preference matter?

p.s i tried playing sej but didn't feel like she was for me.