I think overall, SynthV has one of the best engines. I remember when the demo was released I was like "whoa! Eleanor sounds so clear and real", and I'd really love to use it more, but, again not enough Japanese vocals for me (though, Peaches, you've now get me eyeing Haiyi for the sake of making her sing in Japanese; her voice is lovely). I haven't gotten to use CeVio much (I had the trial on one of my old laptops and ultimately let it go to waste because I had other things going on), but the one thing that stands out to me is that it has a lot of noticeable engine noise/artifacting in the voices. Sasara has it especially bad. I really like IA English, but the engine noise just ruins the vocal for me. I think she would've benefited more from being a Synth V or Vocaloid.
UTAU was the very first editor and vocal synth engine I used, so I'm probably a bit blind on its difficulty. I think unless you make heavy use of the plugins for it, it's probably very difficult. (I would like to take this moment to point everyone to Zteer's UTAU Pitch editor plugin; I couldn't tune without it!)
UTAU was the very first editor and vocal synth engine I used, so I'm probably a bit blind on its difficulty. I think unless you make heavy use of the plugins for it, it's probably very difficult. (I would like to take this moment to point everyone to Zteer's UTAU Pitch editor plugin; I couldn't tune without it!)