One of my favorite subjects
Before I settled down to a conventional lifestyle I spent 7 years as a professional gambler. My primary action was on horse racing, with poker and college football as supplements. I had a lot of interesting experiences, both good and bad, during those years.
I've never played roulette, and never would. Craps and blackjack (single deck only) are enjoyable games but I get bored with them fairly fast, and the house advantage is difficult to beat to any significant degree. The great advantage in betting on horses and poker is there is no house to beat, it's just you against the other player(s).
Nowadays I still play poker pretty often online, and make occasional trips to the racetrack.