The revelation of the correct way to utilize Rinoa's Angel Wing made me reconsider my position towards it.

Anyway, the best ones (for me, anyway) :

Lion Heart -- useful, but, it bores me on less-priority fights (aka random encounters).
Shot -- the variety of ammo (especially Shotgun bullets -- they're good vs Cactuars or multiple enemies, ganging up on you, along with Canister, AP, & Hyper).
Duel -- repetitive > Special. Sad but true.
Wishing Star -- Same reason as Lion Heart's.
Shockwave Pulsar -- only confirmed >9999 HP damage.
Mighty Guard -- necessary for me.
The End -- yes, it's the cheapest, but it's fun watching something cheap.