Which card gives you the best rewards?

It depends EXTREMELY on how YOU value rewards.

Looking just at miles: Typically the same number of miles which gets you a last-minute seat on a domestic coach ticket (in which case it may be worth over $1000) is the same number of miles that gets you two far-in-advance seats on a domestic coach ticket (and in those cases is probably worth only about $600ish) is the same number of miles that upgrades a <$1000 Los Angeles to Europe fare to business class (which would cost you SEVERAL thousand dollars if you bought it outright, and thus it's worth probably at least $2000 to $3000 in that situation).

So that's how differently one person may value miles from another person, on the same airline.

Then add to that the differences between airlines, the differences between how quickly you earn miles with different FF programs and their cards, versus the differences between that and various cashback programs, versus the annual fees of various amounts that you need on many but not all earnings cards, etc, and you can see it's an impossible question to answer in generalities. Versus the giant differences in versatility that exist between some cards.

Perhaps if you describe your situation with a lot of specifics (how much think you'll charge per month, what FF programs you already belong to or are considering, where you live and where you most often travel to or want to travel to, etc) THEN you can start to have a chance of getting some advice (that will then only apply to YOUR situation and perhaps a few others similar to yours).