Difficult question for me to answer, because I like so many kinds of music...
Um, with vocal music, it mostly depends on the vocalist. Whoever's singing MUST have a powerful, belt-out voice, and must not sound at all whiny/screamy, breath-y, or hoarse. They can't sound like they're talking as they sing, either - I usually like songs where the vocalist sings the words more as a slur (that's the best way I can describe it
).
As to the melody and genre, a lot of what I like is passionate music (erg, bad term). Something to which you can belt our your anger, or something triumphant and inspiring, or deeply moving. I enjoy melodies that only take me a couple times to pick up, too - songs that go all over the place aren't as fun.
Lyrics aren't that big a deal to me. Sure, I appreciate music artists much more if they have unique, meaningful lyrics, but when I first hear a song, I usually listen for how well the person can sing, how original the melody is, etc. If the lyrics are good, great; if they're bland, well, that's ok too - it's only offensive lyrics that almost always turn me off.
*shrug* but it's hard for even me to predict what I will and won't like, so it's hard to write down exactly why I like a song.
