Cories depend on the type you are interested in.
My favorites are the pandas-which I can't find anywhere-, and spotted cories.
For tetras...
-small tets-neons, black neons, gold, cardinal, silvertip, and glo-lights.
-medium-serpae, phantom, buenos aires, head and tail light, lampeye, lemon, pristella.
-large- bleeding heart, black widow, columbian.
Just for size differences. This depends on the size and number of tets you want to get. The smaller the size, the larger the quantity you can get.