Agreed - HoN has the absolute best game mechanics in the MOBA world (and arguably the best heroes selection, although I miss some original ones like PL or PA). What makes them slowly fall into irrelevancy is the quality of S2 and their developers. While Dota 2 and LoL kept innovating, the differences between HoN and the beta that came about 3 years ago are relatively minor. 95% of their (painful, btw) updates are new hero skins. They added a lot of shit in their quest of making money off it (started as pay-once, then shifted to premium model, now they just sell vanity stuff) while ignoring basic bugs (e.g. the reconnect bug, untouched since the beginning). And, most annoying of all, it runs infuriatingly badly on OSX, for some reason. The game drives any system I run it on close to 100% CPU for some reason. My bitterness aside, the game mechanics are perfect, so chapeau for that.
Source: MOBA player for 7-8 years, including Dota, Dota 2, LoL, Demigod, and obviously HoN