and apparently Cubase comes with a plugin in that is equivalent to Melodyne or Auto Tune
VariAudio is a nice plugin because you interface with the audio directly in Cubase, vs working with audio out of the program like Melodyne.
I run Cubase 6.5, so the main limitation I have with VariAudio is the inability to create chords/harmonies with a single audio event, meaning in order to achieve this, I have to duplicate the tracks and manually adjust each one.
Cubase 7 apparently comes with an updated VariAudio feature that allows for the creation of chords and harmonies.
Judging from your posts, your goals, and what kind of workflow you're after, Cubase or Logic are the 2 I would recommend.
Although Cubase does have 1 other flaw I forgot to mention. With a legitimate copy, you need to have a USB e-licenser dongle plugged into a USB port. Isn't normally a hassle, but if you have a laptop with only a few USB ports, it may necessitate getting a USB hub so you still have enough ports for your other equipment, such as a microphone, keyboard, and external hard drive for sample libraries.