Kinda hard, each song delivers a different emotion and is meant for a specific mood.
I'm guessing this is an order of how well the songs play their moment, just top 5 though, seriously, all the themes are pretty darn good.
5. Man, as an introduction to a game this song is just catchy, nostalgia is imprinted in your head through visual and sound and it's really good near the end and also used in the plantation, for some reason, but it still works.
It's placed in two great places, the start to get you in the mood for the comedy to come and plantation, a moment in the story which is pretty important but also rather freecaring, you've got some side quests to do, some exploring to do, and a jet pack.
4. It's playful and upbeat, after the various difficulties that is the final boss and real final boss, this theme tries to give you a rewarding sense of relaxation and hope.
Until someone makes an quasi sequel or various mods.
But seriously, it's a darn good way of ending things.
3. Like Sindiewen said, it's a great way of starting things off.
Like Quote you're kinda confused, you're not sure who this main character is, or was, no idea where you are or what you're supposed to do, yet this theme doesn't push you, like your first steps nothing is too hard and the song accompanies you along the way.
Later, you return with your booster 2.0 and this theme is great for nostalgia, in a pretty subtle way.
2. Running Hell is to be honest, one of those themes I don't really like.
But it's great, even if it only gets good for me at the second half while you're gapped between two rows of angels comming out of the ceiling and pavement vents shooting arrows at you with spikes comming out of the floor and some on the walls.
The song fully captures.... yea you get the feeling behind this screw it, next theme.
1. A pretty goofy choice I'll admit, but for me a theme is epic (by the most part) when it fully accompanies the moment and like Balrog, it's not really threatening and doesn't take things very seriously, yet out of nowhere as it comes this theme takes you by surprise becoming serious and dangerous without changing.