I think there's no easy answer to this...
It all depends. If you're looking to write a modern catchy pop song with lots of mass appeal, the I'd say the music is the primary factor here, and the lyrics play more of a secondary role. I don't mean to judge anything at all by saying that, and there are certainly exceptions to this, but just from taking a look at the current top ten singles in sales I would say that most of them are not meant to be lyrically clever, or have a deeper meaning.
If you aim to adress a more mature audience, you most likely won't get away with repetitive one-liners and catchy melody, but people will expect at least some sort of story or imagery in the lyrics.
Of course, it depends also a lot on the genre.
For me personally, the more important factor would be the music, for several reasons:
First of all, I am not very talented at writing lyrics, it just doesn't come to me as natural as the musical part of the songwriting process.
Furthermore, as a non-native English speaker, the first thing I pay attention to in the (predominantly English language) songs I listen to is the music, the arrangement. I really do appreciate a good set of lyrics that paint a nice picture, but I have to concentrate and pay attention closely to properly understand and interpret them, while I can judge and appreciate the musical qualities of a song while doing and concentrating on other things.
Lastly, for my personal taste, songs can be good and very enjoyable without having very good lyrics (or even any lyrics at all, there's a lot of great instrumental music out there), but for me even great and immensely clever lyrics are just words, unless combined with the fitting music and melody.
Again, that's just my 2 cents.
In the end it will be a the combination of both, as well as the choice of what kind of music to combine with what kind of lyrics that will give you a good song.
Very interesting discussion topic I think