The investing app is stepping into the premium credit-card market long dominated by American Express and big banks.

The company is no longer just a trading platform as it launches a premium credit card.

With an annual companion certificate and credits that can more than offset its annual fee, the Amex Delta Platinum provides a lot of value, except for lounge access.

We evaluated 165 popular credit cards across 56 criteria—including costs, rewards, and other perks—to come up with the ...