played a lot of dota back in those days, flying spaghetti monster, CC, and g@.re.na.
sometimes i play alone, sometimes with friends. both are enjoyable for me.
and then one day my friend introduce me to HoN. here's the few key feature that got my attention:-
1) The ability to reconnect after disconnect
2) Records stats, including leaver stats
3) Nicer graphics
4) No map hack as it's server based
5) Able to bind keys
and the fact that it's based on Dota, so there's very minimal learning curve/getting used to.
tried HoN during it's int.beta phase, die....hooked to it terus although during team fight i dunno what's happening because it's too colourful XD
been actively playing HoN for 3 years now i guess.

manage to try Dota 2 also early this year. graphic wise, i prefer HoN's as it's more bright and rich in colours and also the battlefield viewable space is bigger compared to Dota 2.
the thing i like about Dota 2 is that the server is better.
it's by Valve.
sooner or later the players will flock over to Dota 2.

but i'm still playing HoN because all my friends are there and not all of us got the beta key for Dota 2.

so to answer your questions:-
1) i've already tried Dota 2 and currently playing HoN actively
2) friends
3) i would like Dota 2 better if the viewable space is bigger. as of now, it makes me feel a bit claustrophobic. also i would play Dota 2 if all my friends are playing there and HoN server is down lol.