Some thoughts- Pianoscan will read scanned single-voice music and convert it to MIDI--but it's a nuisance to use. Too much editing.

Noteworthy Composer works well;

MusicEase, IMHO, may be a bit easier. My personal pet is the old SongWright, but that's no longer available.

ABCMUS is a fine ABC player, and does a creditable job of setting chords to the music.