You can have either or but most would probably agree it is best with both. However, that isn't the point of this thread.
Beats or Lyrics? Which are more important to you and why?
I place an importance on both. They go hand in hand. No matter how good the rhythm of the song, if it has lyrics that just don't flow, it'll be a clunky song. Same is true in reverse, the lyrics can be profoundly deep, but if the rhythm is off, it'll be a hard song to sit through, or if there's an annoying sound pattern too.
Lyrics are more important to me. That's where the meaning is.
Hmm. Hard to say, likely it depends on the song.
Of course, I'd also say "vocals".... there are songs I like because of the singing, even though they're not in a language I understand.
(And by "beats", do you mean just the bass line? Because while a good beat can be great, the rest of the instruments playing can also be really attracting.)
..sorry, I have a hard time singling out a specific "best" in anything (couldn't pick a single favorite game, or actor, or movie, either.)
As I didn't want to recite generic (albeit mostly true) opinions about the topic in comments and end up not picking each of the options, I voted for Lyrics. Why? Merely because I tend to listen to genres that rely heavily on lyricism, that's pretty much it.