Eh, it's anecdotal, but a NZ friend and I used to 1v1 all the time. We were evenly matched. He had 160 ping, I had 260 ping.
Then OCE server came out. We transferred. I have 30 ping, he has 70 ping. Our 1v1s were just as "close." This tells me that the importance of the decisions we made in lane were far more important than any minor reaction time there could be. Even in "equal skill" matchups, unless you're at the highest Elos the decision-related mistakes are going to be more important than the reaction-related mistakes.
Like seriously, you should know this since you're only slighly lower Elo than I am. If you put yourself in situations where you're relying on reaction time, then you're playing badly. There's a reason why OCE players made it to NA Challenger with ~220-240 ping before we got our own server. They played properly, such that reaction time was never an issue. And no, they didn't play low-reaction champs - I thought they were doing that too, until I realised they were still playing "difficult high-ping champs" such as Lee and Gragas.
You guys would know Keane - he came from KR, but he was living in OCE when he made it to challenger on NA. The ping didn't hold him back one bit. There were many others from the OCE "pro scene" (which is trash btw, but we have a few "stars" that did well on the soloQ ladder) who made it just as high, but you wouldn't know many of them (Raydere, Heavenz are two examples you can Google).