I agree angels are amazing fish ...if you are looking to breed then you probably will only get away with one pair....each angel is different of course, and maybe 2 pair will work...but, you would need a back up plan if they didnt...or go with the one pair to be safe...to have sucess breeding, you will need another tank of 20 gals or so...the 20 gal should be
bare bottom other than either a piece of flat surface rock, or big leafed silk or real plant..thats what they like to spawn on...then after they spawn, and the babies are free swimmers, move the parents back to the 55 gal...that seems to be what works for me best...then you can keep the 20 gal prestine with a bare bottom.. if you are just looking for a fun tank in the 55 gal, get the same sex angels no matter how many you choose...then choose some fish to go with them depending on how many angels you get..some good tank mates for angels for me have been ,
DG, rts or rainbow, cories, br parrots, black skirt tetras, guppies, platies, and ottos...im sure others might have some suggestions, but thats what ive kept with mine...