Like everyone on the internet (you, me, the ISP), the VPN provider can only guarantee a fast (as in response time) experience through his own network. Beyond those boundaries, we're all at the mercy of the greater internet. Even two ppl using the same VPN provider could have completely different experiences because they're routed differently between their own ISP and the VPN provider, and/or between the VPN provider and the game's host system.
So no matter what anyone might recommend, and no matter the claims of the VPN’s marketing department, it's always a roll of the dice. You just need to try a few and see which provides the best results. Perhaps don't commit for more than a month to any one VPN provider until you see if the results are both good and consistent.