There are plenty of sites you can choose from, there are options in this forum, and you can also do a quick search on Google and look for sites that provide reviews from professional gamblers. In my case I prefer sports betting over online casinos, however, I'd recommend you to visit the Bookmaker's review site, they have a rating guide with the best online sportsbooks and betting sites and most of those sites have their online casino as well so I think it will work for you. I'll leave the link here if you want to check it out https://www.bookmakersreview.com/best-sportsbooks/

Hope you find what you're looking for!