Wonderluckplay
Deposit minimums that are printed clearly, rather than buried in a terms page, tend to correlate with operators that are generally upfront about the rest of their terms too.
Mobile performance has become a deciding factor for most new sign-ups. A site that loads quickly on a phone, keeps menus uncluttered, and avoids forcing a separate app download tends to keep players around longer.
Live dealer tables have closed a lot of the gap between online and land-based play, letting players get a similar social feel from a browser tab without leaving home.