HoN and LoL are very different interpretations of the same idea.
Similar concepts :
3 lanes
5vs5
heroes have regular skills, and one ultimate skill.
Items can drastically change the intent of the character.
both games have similar character archtypes ; Carry, tank, ganker, nuker, pusher, etc.
Both have similar strategies.
HoN exclusive :
Denying creeps ; killing your own to 'deny' the enemy experience and gold
many familiar characters from DotA
Ultimate creep is Kongor ; He drops a 10 minute token that allows the user to revive when killed
LoL exclusive :
Certain creeps can give buffs with killed (dragon + golem + ultimate monster)
LoL introduces Ability power ; this allows casters to scale better
LoL does not contain denying or creep blocking ; thus lessening the gap between melee and ranged characters (as cited by their website)
Ultimately, it's preference ; I noticed that people on HoN tend to be more competitive ; and I do prefer it. However, LoL is not bad by any means.