For me simple and selective or unigue games is good because having lot of games will make the site looks not familiar eve after many uses.
Having instant deposit and withdrawal for crypto currencies will make them as good one.
Right now, we can see there are so many unique games which we can try. I see that now, rocket game is giving a new experience for playing gambling. I am sure that in the future, there will be many more new gambling games that will attract gamblers to play. Maybe the gambling website doesn't have to use KYC for the members, so I think many gamblers will join with them.