Depends very much what you're playing really. Some metal and rock songs will use that lowest note a lot, almost like a drone and for that, it's much easier to have that lowest note an open string.
When playing a 5 string, muting is really important, that low B string just wants to ring out all the time.
If you're going to tune up to C then make sure you fit lighter strings otherwise you'll be putting a lot of load on the neck.
I used to play a 5 string in my band because I played most riffs off the open B string but for most stuff, I preferred a low tuned 4 string.