Power Tracks Pro is an excellent value for the money ( around 50 Usd ). It's made by PG Music, the same folks who make Band In a Box. In that price range, and also an excellent value is Cakewalk Music Creator. Both have full fledged sequencers and editors onboard.
If all he ( or she ).. wants to do is play back premade midifiles, then an app like Van Basco karaoke player is fine, and it's freeware to boot
If your friend wants original arrangements but isn't so much a "Do it Yourselfer".. in other words, he does not want to play pre made midifiles, but he doesn't want to make sequences from scratch, he could check out One Man band, which plays Yamaha style files... Chords and style parts can be recorded in step or real time.
Regards,
AJ
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AJ