For me, it's always the reputation. Everything stems from it so you can't really go wrong, they wouldn't have a good rep if they are cheating their customers or if they are being rude to them right? So I am pretty sure that reputation would be the greatest indicator that something is right with that casino that we are choosing.
Casinos with a good reputation often create conflicts with their customers, which goes against that customer. Now if a good reputable casino doesn't have enough games then it may not be your choice. So taking the opinion of the community can be a good way to choose a casino. Because if an experienced player gives a good review about a casino, then new players are interested in doing more research about it. A casino's reputation will be good as long as they work honestly with their customers.
The conflict between casinos and the players will always be exist because there is no perfect casinos in this world but as long as the casinos can solved the issue i think this proves that they care to their costumers and their reputations and indeed review from experienced players sometimes necessary because it can be good reference to other players to try some casinos and about the games currently there are many reputable casinos with plenty of games available so it won't be hard to find them