The power bank will draw only as much current as the charging circuit needs.
If your only concern is getting a fast charge, get an adapter with the highest voltage the charging circuit can handle, with a little "headroom" on the current capacity. Maybe 20 Volts, 3 or 4 Amps. (Don't worry; it likely won't draw more than 2 or 2,5 Amps, ever.)
Now, there's a catch: High speed charging means higher temperatures inside the battery. And that's going to shorten its life. Your choice: long life, or fast charging.