Jim, I'd agree that guitar, indeed is very similar and should be included. In fact, based on your comment I saw the English as being most closely related in its capabilities to a guitar: it can be superb for both, chords and melodies, but not independently and at the same time. Duets are probably most similar to piano/organ. Anglos are more like a mix of harmonica and piano, more related to melodions: some chords, any melody...( I actually always saw and used it as some kind of glorified hand-pumped chromatic harmonica with extended chordal capabilities). I'd agree that any 4 stringed fretted instrument can probably compete in the chordal department, if you're willing to settle for inversions as your only option in getting ALL the chords. How successfully can they compete? Not as successfully as English.... besides inversions, some notes may not be physically reachable...
...isn't it a chord monster, rivaled only by a piano? In my experience it totally is, as any theoretically known chord can be easily played.
I don't think anyone who has tried the English has said it's not good for playing chords. What is considered between difficult and impossible is to play a constant chordal background simultaneously with a melody moving at a lively pace.
As for the piano being the only rival for chording, I would add to that at least the lute, guitar, and various other stringed instruments.
Edited by harpomatic, 12 November 2017 - 06:23 PM.