I hate to say it 'cuz it's non-committal but...what works best is whatever you make work. For me, I wouldn't use hand-drawn or iso or whatever because of the texture and colors being so dominant. If you turned those way down so that they are just faint colors (more like a grungy paper) then you could use hand-drawn. As is, I'd use a shaded relief which is something less than a real height map...think of Pasis style mtns as opposed to me style mtns.