The subreddit r/churning is specifically for maximizing credit card rewards and they have a thread where you can ask for card recommendations.

They also have a flow chart that shows best sign up bonus offers depending on what you’re interested in (travel, perks, cash back).

If you’re interested in Delta or Marriott then I’d check sites like DoctorOfCredit to see what higher sign up offers are currently available. I got the Delta Gold Amex with 90k points not that long ago which was pretty good but they fluctuate often.

Sign up offers are a huge part of the return on getting one of these cards so it’s worth researching those.