I'd date Rowlf, definately. Maybe Robin if he was older. But definately Rowlf.
Actually,funny story about this. My sister comes home one night and she tells me that she and her boyfriend decided I was going to marry a muppet. I asked which one, and they said they would let me decide. First thing I thought was "Well not Kermit, because that would be dangerous with Miss Piggy". Long story short, Rowlf and I are engaged.