Auto tune 4 vs. Pitch Doctor vs. PurePitch ect...

[Glenn75]

I need to find an effective easy to use pluggin for intonation and pitch correction. I need a pluggin that can correct problems on the fly for all instruments not just voice. I may need to use it for complex samples as well. What are the pro's and cons of each? I am leaning towards Auto Tune 4 because it seems to be the industry standard but are the other choices just as good or better? Is Auto Tune 4 the standard because of marketing or am I on the right track? Incidentally I already own Speed but it doesn't really accomplish what I am needing to do in many instances.