ACE Studio

I use this, and while it can be very effective, I'd argue that the default voices are not particularly strong or passionate. A recent update added a couple I think are considerably better and I love that it will create a voice that you provide the samples for, even if the samples need to be really clean. You can use your own voice, even without singing. Also, some voices sound better in different keys or octaves. Just selecting the right one can take quite a bit of effort.

It does offer very fine editing of consonants, vowels, as well as a number of timbre items such as air, tension, breath, energy and formants. The audio to MIDI is also quite accurate so you can sing in stuff. But I've found that to get really good vocal requires a lot of editing and tweaking. A lot. My best results have come when I enter the MIDI, then convert.

All that aside, highly recommended, even if only for scratch vocals. Subscription software, but considering the features, well worth it.