To be honest, I've never come across a species I didn't like, though occasionally there are particular forms I don't like (usually captive-bred colour morphs or mutations). There are species I don't have much interest in (chimpanzees spring to mind), but none I actively dislike.
Rock Cavies are great; nice chunky rodents. This one was in the bottom of one of the run of South American primate exhibits, though I'm not sure what species it was mixed with off the top of my head - the run has Buffy-headed Capuchins, Venezuelan Red Howlers and a selection of callitrichid species.
