Although a very careful consumer can probably avoid the pain of a high-cost credit card, I would have nothing to do with the c/c companies mentioned so far in this thread. They're not in business to give away "free" miles - I suspect that internally they refer to them as "bait".

If you never carry a balance and do nothing to attract fees (e.g. don't charge anything outside the US), you can ignore my thoughts and enjoy the benefit.

For the rest of us, a generous credit union is probably a better choice. They still depend on people paying interest on carried balances to pay for those miles, but often don't surcharge forex transactions and aren't so quick to pile on fees and penalties. But ymmv so read the fine print.