I like JustWatch. Search for a show, it will show you where it's available for free, where it's available with subscription, and where you can buy it... and not just the major services, but TV channel sites, too. (Note, I'm Canadian, and it's showing Canadian TV, like CTV. No idea if they just happen to be Canadian, or they show what's available elsewhere.)

Shows what's trending across services.

Also has a "new" tab. Select which services you subscribe to, and it will show what's added to each service. It seems to remember my service selections via a cookie, so I don't even have to bother making an account.