I think the Tank could beat a rhino, because once the rhino gored it, the tank would pick it up and tear it to peices, the berserker would just pick up and chuck the rhino as it ran at it.
Between the tank and the berserker, hard to say, they both take huge amounts of punishment, and are both super strong. I would have to say the tank though because it could throw huge boulders at the berserker from a distance and beat it down or wear it out (supposing the berserker didn't grab them or throw them back or dodge them).