Look at a sport, lets take NHL - 50 years ago vs now, the players now are significantly more skilled - but its by evolution of the game. Better gear, better coaching, better development. Nowadays in DP, people have WAYYY better computers etc.. - which let bigger maps come, which pushes the jumping/aiming limits that older players never had. I had a ball mouse and got 30fps when I first started this game, now I have 1000 fps consistent and pretty quality gear. I would not be able to play Renoir etc.. with my first setup.
I think Shk is the best player in my opinion, because he's been a top player for the longest time. Players like Spain/Proza/Jeo and a few others have been good competition recent years (but I'd argue the games been at its worst competition-wise) - but they have not stayed on top for the same time as Shk, nor have they experienced the same competition.
Personally, I found dd9/bix to be the players I've struggled against the most in this game. And for whatever reason, dystro has been the one I've struggled the least against (he was definitely always an upper-tier player in the matching scene, but I'd just always hit the most BS shots on him consistently).
At the end of the day - anyone's who's won any form of money/prize from the free game, are the best players in the game. You got something outta a free game, you the real winners.