(...)I'd much rather use comet than Throw, Manipulate, Morph etc. When certain E.Skills or items are needed I temporarily equip morph or manipulate but otherwise I only equip E. Skill and Steal(...)
Throw, I'll admit, is probably much less bang for its buck, literally. Chances are you won't be throwing valuable items (if you even can in this game...shows how much I use Throw

) and the items worth throwing are generally expensive. Manipulate, on the whole, is really only useful when looking for pesky Enemy Skills, since the majority of enemies don't have attacks that equal your own in terms of power, but I still use it from time to time. Morph, well, Morph is only good on Yuffie's Conformer, in my opinion. Only time I use it.
(...)and who uses Deathblow anyway?
Deathblow can be particularly useful with Vincent's "sniper rifle" weapons (the ones that give you 255% accuracy...I think there's only two), since it has a low chance of missing, but by the time you get one, you can probably do reasonably good damage anyway.
But still. I'd rather use attacking Command materia over Comet. I was never attracted to the magic in this game. Heck, by disc two, I have no use for it, which is really sad, because it's always been my opinion that magic attacks should always overrule physical attacks in damage, but the Final Fantasy series, for the most part, with their leveling systems, tend to allow physical power to overflow with greater benefit (f.e. 255 strength on a perfect Attack Reels with Wakka and Piercing ability) than magic power. Who wants to cast a timely spell that costs magic power and isn't that effective? On this game, Knights of the Round is the only true, good, magic-over-physical attack, though a hearty round of 4X cuts from powerful characters isn't that far off.