Autotune plugs..

I use the one that comes with Cubase where needed.  For tuning harmonic content friends sware by Melodyne.  

Started with Waves Tune LE. Went to Melodyne Studio and never looked back. Waves is okay but sounded a little unnatural to me, plus the workflow is a bit quirky. Melodyne sounds very natural and you can do a lot with it. I try not to spend much on plugins, but Melodyne was worth the money.

Make it a fourth. You can make it super transparent.

Another melodyne user here. I love it - always seems to do a good job.

When working on my own songs, I tend to use it like this -

I sing my vocal take and then use Melodyne to tune it 100% - to where it sounds perfect and artificial. I then sing along with that a few times in my headphones to really get my pitch nailed. With my guide vocal melodyned 100% in my headphones, it's easy to hear when my own pitch drifts while tracking the vocal. That way I'm left with a vocal take that's pretty much in tune but I haven't melodyned it. I use melodyne to make a perfect guide vocal to practice and sing with. Then if my tuning is off anywhere while doing the new take of the vocal, it's only by a tiny bit and then I when I use melodyne, it's super transparent.

Of course no artist I work with sadly is willing to put that kind of effort into tracking a vocal, so it's a technique I use just with myself.

Melodyne can still mangle things - in a different way than. Autotune. Sometimes it can do a number on the esses,, so you really have to listen

I have Melodyne Studio, but the last few years I've used Melodyne Editor exclusively as a Cubase plugin. It's polyphonic, so as well as pitch correction you can use it to alter the notes in a chord or to reveal the notes in a commercial production, if you occasionally need to do that.

I have had them all, but since Vari-Audio came to Cubase, its all I need. Its a fantastic program with no bridging and no cpu bog. Also, since it is built into the program, it has no added expense.

I used to use Melodyne too, then Digital Performer introduced its own pitch editing capabilities and I've used that since. Can't tell much difference and I much prefer the fact that DP's pitch editing function is tightly integrated.

I must say though that I never do any editing on artist's "mistakes" unless specifically asked. So it means that my experience with pitch correction is modest at best.

I always fix any pitch issues in my own vocals that bother me. DP's pitch tools are great, and I tweak the offending bit by ear, not snapping it to an equal temperament pitch grid. Autotune is usefull if set to the proper key and used consciously, especially for background vocals where you know what you want them to sound like.

I'd like to try Melodyne.

YES!!

No high-fructose audio corn syrup for me, thank you very much!!

Nothing I do or sing for others has any sort of autotune, melodyne, etc on it.
RULES:
1. If you didn't sing it right, sing it again.
2. If you can't sing it right, let someone else sing it.
3. Some singers are routinely 7 to 12 cents flat due to hearing difficulties using headphones. Manually correcting that doesn't count.

well.... I did warn everybody

There is room for it all, but the "corn syrup" is ubiquitous in the music diet of today, no matter it's killing music, I hear it slathered on everything for the 2 seconds before I shut that shit off...