Fine, I'll start.
I instantiated the current demos of all three in a Logic project, testing on a female vocal part.
Here are the pros (+) and cons (-) as I've determined thus far:
MELODYNE PLUGIN
(+) time stretching
(+) time quantizing
(-) no export of MIDI (except full versions)
(+) resizable window
(+) horizontal scroll ball
(+) vertical scroll ball
(-) no navigation of play position
(-) draw curves
(-) no auto mode
(-) must re-record into plugin upon edits of Logic project (that is, inserting or removing time, moving audio, etc)
(+) great pitch transpose
WAVES TUNE
(-) no time stretching
(-) no quantizing
(+) export of MIDI
(-) small window and not resizable!
(-) no horizontal scroll ball
(+) vertical scroll ball
(+) navigate play position
(+) draw curves
(line, curve)
(-) no auto mode
(-) audio updates on project structure change, but not visual update, so still have to re-record into plugin
(+) great pitch transpose - seems as good as Melodyne, even +/- 4 semitones
AUTOTUNE EVO
(-) no time stretching
(-) no quantizing
(-) no export of MIDI
(+) resizable window
(+) horizontal scroll ball
(+) vertical scroll ball
(-) no navigation of play position
(+) draw curves
(line, curve)
(+) auto mode!
(+) automatically updates if project structure changes
(-) bad pitch transpose - chipmunking even with Formant turned on
Feel free to add to this list or comment...
Thus far it looks like no single plugin does it all, at least in terms of encompassing the features I want. I currently have the light version of Waves Tune, but would like to have the features (such as the pencil tool) only available in the full version. Still, the upgrade path costs as much as buying one of the other plugins!
The time-stretch features in Melodyne are very nice, although one can approximate some of this with the option-drag stretch features in Logic.
Yes, I'm rather obsessive.
mk3