The most powerful hero is SkywrathMage, however you need be careful with this hero, dont play very suspicious else you will get reported and might also receive manual ban.
then there is close to powerful assemblies for meepo and arc warder.
All other heroes are average, and most likely you will not carry solo with it.
That way you need some good Utility assemblies, like o9k.hud, Divine.BeAware what will show you allot of good information and some automation assemblies like o9k.AutoUsage, item manager... and you will be good to go.
It looks like you're new here. If you want to get involved, click one of these buttons!