Preference: LoL
LoL - 8/10
HoN - 5/10
DotA - 3/10
Game Speed:
LoL - Slower game speed, Team fights are just as fast on all 3, but LoL with their more basie graphics allows for more thought and understanding especially in early game. Lanes are better defined.
HoN - Things seem to happen faster than can be comprehended
DotA - Because this game was based off the Warcraft III engine, the game speed really wasn't taken into account so it can't be blamed
Dealth Re-cap:
LoL - Shows all damage done in the last fight to show what killed you and what type of damage it was
HoN - Nothing, just a big LOOSER across the screen
DotA - Nothing also
Items -
LoL - Recommended items, then a really detailed split out of items and what they do. I really like this format better than the rest, it's simple and the stat modifiers are strait forward as there are only a few (Crit, Damage, Physical/Magic Damage reduction, Attack speed)
HoN - Recommended items are good, but there are just too many options and stats to keep track of for a newer person (Str, Int, Crit, Damage...) While true to the Dota style of "shops" and divisions of items, it's not that user friendly. Support should be defense... Polymorph? Huh?
Dota - Revolutionary at the time, but very confusing building items, secret shop doesn't help the process, but again for the limited mod, it's pretty cool
Internet game play -
LoL & HoN have good team builders and are built for online game play.
Dota - Basically LAN only game play especially since the community for this game has adopted HoN or LoL for their game play for this style of game
Free-to-Play -
All these games are free to play (Well not really Dota, you should have to buy Warcraft III, but if you don't have a friend with it already, FAIL!)
Level Game Play -
LoL - has the ability to have special spells and Runes that based upon level and time played can give an advantage before the game even starts. This includes boosting anything from Crit Change, to mana Regen to overall Health. The Spells come Automatically with level up, where the Runes can only be purchased with points gained through game play
HoN - Every time the game starts, everyone is equal, not outside boosts are allowed or available.
Dota - Just like HoN, no outside ability to buff character prior to game start.
Character Picks -
LoL - each team picks from available champs, duplicate champs can be used, but not until the loading screen when both teams are locked in, does the other team learn of the opponets team build.
HoN - Difference game styles are available, but the most used is a Free pick, where both teams pick from the same available characters and only one instance of each character can be on the map at a time, no duplicates.
Dota - Each faction has their own set of characters and only one instance of each character can be present on the map at a time.
That's my basic understanding, please feel free to add, subtract, or correct anything that's incorrect.