I like Van Basco's Midi Search.Where can I download professional quality midi files?
http://www.vanbasco.com/midisearch.html
Once you have the midi you can improve the quality a lot by swapping GM instruments for better ones in the Korg (especially guitars and strings) and re-mixing volumes.
If you like 70's Easy Listening Pop (Eagles, Elton John, Bread, America, Air Supply etc.), I have quite a collection and happy to share some. All mine come with lyrics and chord prompts.