Carbuncle is always one of my favourites, because he is so damn cute.

Practically though, in real terms I hardly really 'used' Carbuncle. Reflect is very situational and forces you to use items, which isn't always a bad thing, but still tricky to overcome and adapt to.

I never played IX, though the improvements of haste, protect etc. seem to be better. Sort of like a souped up Mighty Guard.

I wish Carbuncle was seen more as a summon though. It's very rare as a summon, especially later in the series.