While I was recently at an Apple Store, I decided to go for a Lightning to USB Camera Adapter. Testing iOS 13 gave me a couple of good reasons for that, since it provides support for USB drives and mice.
When I plugged a USB mouse into the adapter and connected it to my 10.5-inch iPad Pro, it worked. While using a mouse to control an iPad is great news, it remains to be seen how useful mouse support in iOS overall will be. One distinct advantage is that it lets you work further away from the iPad so you can use it more like a traditional desktop.
Next, I tried to connect to a USB thumb drive and immediately received an error saying that the accessory requires too much power. Drat.
Fortunately, I managed to work around this limitation by connecting a powered USB hub to the adapter and connecting the thumb drive to the hub. The disadvantage of this solution is the amount of equipment involved: a USB cable from Apple's adapter to the hub and the hub's beefy charger. I would prefer not to travel with such a collection. In addition, the Lightning to USB camera adapter only supports USB 2.0 speeds, which are not ideal for fast data transfer.
So I (figuratively) kicked myself when I learned that Apple is selling another Lightning to USB adapter that works better for this scenario: Lightning to USB 3 Camera Adapter. It costs only $ 10 more and supports USB 3.0 speeds, at least on iPad Pro models. More importantly, it has both a USB-A port and a lightning-through port. The lightning-fast port is useful because you can connect a standard Lightning cable to it and connect that lightning cable to one of Apple's tiny USB wall chargers. Then it can charge both your device and power supplies as a thumbs up.
Another option is to buy a thumb drive with a light plug. Yes, they exist, but most people already have a collection of standard USB flash drives lying around.
The real question is why Apple continues to make and sell the old, minor Lightning to the USB camera adapter. I can't imagine that there is a big difference in production costs between the two adapters, so the only advantage of the older adapter is its lower cost and slightly smaller size.