NV Crashies imo
Idk much about other regions but in NA it's Hiko, Crashies and ShahZam (in no specific order)
Also all 3 have very different playstyles even though they play the same agent.
For example :
Crashies doesn't focus that much on utility and relies on his super insane aiming skills. He is the best sova in terms of k/d.
On the other hand, Hiko has a slow, methodical and utility focused playstyle where he is dedicated to support his teammates (Iron and Bronzes call this baiting and think this is bad coz they don't understand the game). He is the best sova in terms of utility usage. (He has the highest number of shock dart kills)
ShahZam is a mix between both. He has sick aim as well as good util usage and support skills. Also being one of the best IGLs in the world adds to his impact on the match.