Good points. The biggest SD card I have handy outside my cameras is an 8GB unit, not large enough for my needs. You don't need a "fast" one, you're not going to stream video off of it. You can get a 64GB SD for about $25-$35. You can get 64GB USB drives in the $19-$30 range.
The primary advantage of using an SD device is then you still have the open USB port in your truck for other uses.
We've probably all got one of older-style "thumb drives" - sticks which protrude a couple of inches out of the USB port. I personally don't like that in the truck, because I have other things in the console that might bump the stick and damage it, or more likely, the USB port. If you're going to get a USB device, I suggest one of the low-profile drives. They barely stick out of the port when plugged in, and you're less likely to cause unintended damage.
There are lots of brands. A 64GB version runs up to $27. 128GB runs up to $45.