For Raw it has to be "Across The Nation". Loved that song and it fit WWE Raw very well at the time.
"The Beautiful People" was perfect for Smackdown back then as well.
I hate the current WWE Raw song. There is nothing raw about it at all. A bit like the show itself now sadly. It is a terrible song in all seriousness, it just makes me think of poopy jokes, star wars promos, burials of young talent and Michael Cole mispronouncing wrestlers names. "BA-TAY-STA!"