Safety & licensing: Who regulates the operator, how transparent the corporate ownership is, and what player-protection controls exist by default.
Withdrawals: How quickly money actually leaves the operator, how predictable that is, and what limits or fees apply on the way out.
Bonuses & value: Whether an offer is winnable in practice: wagering multiplier, what it applies to, max bet, game weighting and expiry.
Game selection: Breadth and quality of the library, the studios behind it, and whether the good games are findable.
User experience: Registration friction, navigation, mobile performance and how honest the interface is about cost and risk.
Payments: Whether the deposit and withdrawal rails match the market the player is actually in, and what they cost.
Customer support: Reachability, response quality and whether support can resolve a payment problem.