Next best card, or next best non-AMEX card?
I'm pretty sure this info is already here scattered throughout the site, I guess you just need to know where to look for it.
Besides, I'm not sure there's 1 absolute best card. There's a best for earning rewards, best for benefits, best for churning and probably some other "bests" also.
Then again there are cards which wouldn't qualify as the "best" but could be considered a must-have.
For example the JetBlue card, for anybody that flies JetBlue a lot it's an absolute must-have.