i've been playing for a very long time, (since '79) and have given most systems a shot over the years....dnd in all editions, aftermath, space opera, gamma world, MERP, Marrow Project...etc...
for me, the appeal of hero....its a more 'mature' system than the d20, no 'classes' to pigeon -hole a player into, no artificial ranking system that does little more than play into the munchkin/ power-gamer /lawer hands....hero, requires forethought in adventure and character creations, as a result, a certain depth is created that is lacking in other systems. Also, DnD (as an example) began as a WARGAME !!! a tabletop, minis game that branched into an rpg, (i was around then, and played it, remmember 'chainmail'? little grey spiral-bound book?) it (DnD) still retains those elements....that find it, kill it, take its teasure while chanting 'ECKS-PEE', ECKS-PEE' feel..... most following rpg's borrowed from the DnD model, hero from the beginning (I had the blue box, with the GREY champions book & microdice) 'felt' different, still does and probably always will.....a feel of sophistication
did that make sense?