White - Probably Rosa. She's really complete as a white mage and can do many spells, and do most of them on all the party at the same time, which is really useful.
Black - I don't think Terra should have been in that category because she does many greats healing spells too, but from your list, I will say it's a tie between her and Vivi because they're both incredibly strong.
Blue - Quina, but maybe it's because they're the one I use the most, because Strago is quite great too.
Red - Celes for sure. She's so strong and badass and could kick pretty much anyone's ass.