Not sure if that last question was for everybody or just me, but I will answer it. I am into sports betting so you might have better luck asking someone that’s into casinos.
However there isn’t one fits all, as their traffic will differ from yours. Yes they can point which games seem to be more fun and eye catching, but this is something you would have to try on your own.
For example I noticed for my traffic is that high numbers catch people’s attention. I run a sports betting website but I had this banner once, for a month about poker, and and some high numbers of bonus up to 5000£ I think was the numbers. I got a lot of clicks on it and even 5 sign ups.
BTW you can always ask your affiliate managers on what’s the best performing tool and give it a shot. Even better, you can point out where your traffic is coming from, and they should be even able to give you specific numbers for that geographic region.