Need hints & advices concerning summoning...

[Semigall]

I played singleplayer against AI many times and came to conclusion that i really like summoning rituals as they seem to be most helpful ones in many hard times.

But what i want to know from the experienced D3 players is:

What D3 nation is most powerful in summoning rituals ? What would be the best pretender desing to suit well with summoning ? And what would be the best research path choice for summoning ?

*edit*
With summoning i mean also everything similar, even if it's called in game 'binding', 'creating', etc.