re : kenyi and convicts

Quick question everybody, what is easier to care for, a kenyi or a convict? i only want 1 type of specie in my soon to be new tank. Another question is how many gallons to 1 convict or kenyi? I am planning on getting a 20 gallon tank. I saw a 16 gallon gorgeous looking tank that i really like. Can i keep at least 2 cichlids in a 16 gallon tank? 20? Where can i buy a kenyi? I dont usually see this type in the pet stores.

Please get back to me and thanks!