I am partial to angels, a 100-gallon (4ft) will let you keep just about any Centropyge / Paracentropyge. For larger angels, I think you could do the following:
-Smaller Genicanthus (Spot Breast, Watanabei, Bellus)
-Smaller Chaetodontoplus (Singapore / Mesoleucos, Black Velvet, Blue Spotted)
-Apolemichthys (Cream / Xanthurus, Red Sea Cream / Xanthotis, Bandit- if you can find a CB one, not sure if Karen Brittain still breeds them but I’m sure they won’t be cheap)
For most other large angels IMO they should have at least a 5 x 2 x 2 in my opinion and some need really big tanks.
Butterflies are nice too. If you’re willing to pay a bit more for a fish, I would consider a Burgessi or Mitratus Butterfly. A Copperband might also be fine but they’re not easy to get feeding.
Other than that, Clowns, Damsels, Gobies, Blennies, Hawkfish, Wrasses, Basslets, you have many options in these families.