As has been said, there is no difference in charging performance between USB 2.0 and 3.0. The same is true with USB-C to USB-C cables.
If you want a USB-C to USB-A cable for everything, including data transfer, then get a USB 3.0 one. If it will only be used for charging various devices then get a cheaper USB 2.0.
If you want to future proof then get a USB-C charger and USB-C to USB-C cable. More new devices will be coming with USB-C. There is a power transfer limit within USB-A, so your current setup won’t support USB-C Power Delivery. And there will be no future innovations involving USB-A connectors.