Voice: maturity, voice quality, suitable with song, etc
Sur: not much that can be broken down into
Difficulty of song: Mere Dholna vs. Lakdi Khathi
Versatility
Energy and power: ex-Dastaan...without the right energy and force, there is no way that song can sound right...
Emotions: not facial expressions, but in the song. who wants to listen to Tujhse Naraz Nahin happy, romantic, etc
Improvisations (extra harkats): ex- Tanmay singing Dupata Tera when he sings the part that supposed to be on the instrument or little bits here and there
Performance: dancing, confidence, not looking scared out of your mind, playing with cameras...just overall comfort on stage...interesting to watch
Underrated- do you just go for the underdogs? not go for the most talked about, because they're not perfect
Innocence
Comparison to original
One really good song
Other
For me, I can definitely say that hands down, sur is THE most important when I'm listening to one of them. After that is the energy and right feel/emotion. Difficulty of the song is important, but if it's not sung well then it doesn't matter...but if someone sings Lakdi ki Khati well and Mere Dholna pretty well, but not quite, I would probably like Mere Dholna better. Voice and Performance don't really matter that much to me to be honest. Improvisations...only if they work in the song, because there are so many that abuse it and just add improvizations like crazy and it just doesn't work. I pay no attention to underrated and overrated...but I do kind of favor my favorites, which I shouldn't do...and one song can push me over the edge towards one singer over the other like today with Abhijeet's Dastaan. Innocence is irresitible...but I try to avoid even paying attention to that. So I am admitting some of my inadvertent things when I watch a performance that shouldn't influence me when I'm watching it.
Anyway, this was a long ramble, and I want to know how you view a performance and then rate it and pick your favorite singer. I think people tend to favor the ones with good voices and those that are underrated.