Anker is perhaps best-known for its line of portable batteries. The company's PowerCore+ 19000 unit is a solid option, and right now it's $85 on Amazon. That's a $45 discount from the original MSRP, and $35 below the usual price.
This battery is equipped with three USB ports — one Type-C, and two Type-A. The Type-C can provide up to 27W over Power Delivery (USB-PD), plenty for phones and tablets. It can also charge some laptops, but many laptops won't accept anything below 30W. As a bonus, the battery can act as a USB hub when connected to a computer.
You can grab the battery from the link below. It's not clear when the sale will end.