I am currently GMing D&D 5e campaign, and just about to start RGQ one. We ended old Runequest campaign last year. From my point of view, D&D 5e starts with unified and easy simple mechanics. But, when characters advance past 5th level, they all start to have whole lot of special feats, skills etc. and game complexity skyrockets. At higher levels, Runequest is much more simple to run .