Based on statistic, Raging waterfall is the best among them. This might be the reason why there are still gamblers use VPN in order to access certain games, because it's better than the allowed games.
No sure if VPN usage is worth the risk. This is how one's account gets linked to a number of strangers he has no idea about. Imagine risking your money, making some good profit only to be blocked due to VPN use. And trust me, those game providers do way more tracking and information gathering than we know.
I at one time the slot demo mode temporarily disabled in 3 of my unverified accounts of different casinos because I had gone past the limit in one casino (to be fair, I was so bored and Idle that day)

As long as the casino allows you to use VPN in order to access game due to the restriction by the provider, I dont think it will make any issue later because logically the casino is the one who is responsible for it since they allow it.
I've experienced it myself because some of my favorite providers are not available to be played from my original IP such as Relax, Push Gaming, Netent, etc and I use VPN in order to play it in few different casinos.
Of course I have to ask the support of the casino first if it is allowed or not, most of them allow it and there is no issue at all for years now although I did not win much from those providers (maybe the biggest one was around $1k only).