Another +Anker here.
Decide:
- if you want a USB C socket (you can still use a USB-A -> USB-C, but that means sorting a cable you may not have)
- What fast charge compatibility you want
- How many ways you want. If more ways is important, you may have to compromise on the first two
- if you want to plug straight into a socket, or you don't mind/want a mains lead
Ravpower are equally good and worth a look, too.