I believe the general rule for angelfish is 1 per every ten gallons of tank space, but that would not include putting 1 angel in a 10 gallon tank. I think the smallest recommended tank size is a 20 gallon high. I prefer the koi and sunset blushers, but I have 6 koi and 1 blusher currently in a 55 gal. grow out tank, so I am biased. They are all beautiful, and I think you will just have to look at a lot of breeders websites and decide what you like best. You also should keep in mind that some of your angels may pair up, and that could cause problems in your tank for the unpaired angels unless the tank is very large. How big of a tank will you be putting them in?