That's a really really tough one, as gouramis are probably my second favorite fish (after loaches). That said, while there are good things to be said about pearls, moonlights, true gouramis, dwarfs, honeys, and sparkiling, my favorite is probably the ubiqitous blue gourami in the Opaline color morph. They're big, but not too big, aggressive but not too aggressive, colorful without being cartoonish, and they have definite personality. I found pearls to be much too timid for my liking, and as gorgeous as moonlights are, I understand they are even more timid.