if you like schooling fish i personally like harlequin rasboras. they arent as skiddish as cardinals and they wont bother your angels. i really like your angels by the way. they look great. another option to replace the guppies are bloodfin tetras. they also keep a tight group. i keep cardinals and rummy nose tetras in my planted tank and i think its a good match. (im a sucker for rummy nose though) the rummy nose are quite active and great schoolers, and their little red faces remind me of an alcoholic. lol. those are my top community fish anyways, but there is so much out there.