Carapos are the most available in most lfs. Would stay away from carapo as they get big and aggressive. Will need 4x2 tank for it.
Tiger or zebra will be fine but as long as u have a hiding spot out of the way of the polys then it'll be alright. Keep the polys well fed. Not as aggressive as carapo and will leave polys alone.
Big thing with them is if stressed then can lead to not eating and dying. Cant tolerate aggressive tankmates.