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.
I have an opposite opinion about this. If a site has a lot of games, it means they will attract all kind of people and people will not have to move to another sites in order to find their favorite games.
Secondly all the good sites have instant deposit and withdrawals and hence this feature is not something unique.
Contrary to your opinion, not all sites have instant withdrawal but maybe instant deposit. I have played on a site where it became an issue getting my money. The delay even became scary but I was later paid the money in full.
You are very right on having varieties of games, I am that type of player that would find a site with few games uninteresting and start searching for other sites, there is nothing like having so many games on a site, its better the players are confused on what to choose that to start looking for. For me, I just like a simple site with many activities. But the most important thing is a reputable site that would pay completely at the end of each game.