I think the best compositions (as in how well the music is composed, not how well it sounds) can be found in the 16-bit era.

A Contest of Aeons from FFX

I think Last ninja, the wilderness is one of the greatest songs for a vidoegame ever. Even if it was on commodore 64:)
Sorry, I don't know how to embed...

It has to be mentioned:)

Actually, the whole game was full of great music.

If someone who knows how to would embed Last Ninja, The Wilderness that would be great. And maybe also Last Ninja, Tha Wastelands:) They are both brilliant:)

They can be found under those titles on youtube.

I'd pit Actraiser's music against any game soundtrack, ever.

baten kaitos

violent storm
http://www.youtube.com/watch?v=MwzWySLG7iM

supreme ruler of the nine hevens
http://www.youtube.com/watch?v=eK5cRPzYa2w

the true mirror orchestra ver.
http://www.youtube.com/watch?v=vnsKxmpjqUs

those are good examples

Then there's star wolf's theme, zelda's themes, mario's, megamans, can't think of anymore at the moment.

Hyrule Field Theme - Ocarina of Time.

Sorry, double post

I agree. Classic song