What Factors Determine Successful Singing?

It's difficult to determine why one singer sounds really great and another just so-so.  However, if I were to list the factors that make for successful singing, I would include these:

1. Did you sing on key?  (If not, the rest of the items don't matter, you blew it.)

2. Is your voice even, i.e. not choppy or of uneven quality, throughout?  (You should be able to move from chest voice to middle voice to head voice smoothly and seamlessly, and your voice should not break.)

3. Does your voice have warmth, timbre, resonance?  (Are you learning to use the natural resonators in your throat, nose and chest?)

4. Does your voice have strength and stamina?  Does your voice sound strained, or do you hit those high notes with ease?

5. Do you sing with feeling, i.e. do you express the message of the song convincingly, as if you really feel the emotions the song tries to impart?

6.  Do you have "the IT factor," some attribute to your voice that sets it apart from everyone else, probably from a combination of tone, technique and all of the above.  (If not, then you probably aren't going to be a rock star, but you can still sing successfully with your band.)  You know when someone has this factor; when you hear them sing for the first time, you will exclaim "Man, that guy (or gal) has a terrific voice!"

I think "the IT factor" may not emerge until the first five items in this list have been fully mastered.