I'm a Scamp
owner, but that's mostly because I found a used Scamp
before I found a used Casita
when I was looking for both. They have more in common than they have differences, esp the older models than came from the same roots, so making a choice based on availability, price, floor plan or even color is still going to give you an enjoyable camping machine.
BTW, the advantage of a travel trailer over a pop-up is the setup convenience, esp in bad weather, but where a pop-up excels is having lots of space and lots of 'connection' to the outdoors when you are set up for a while in a rustic CG, kinda like spending time on the porch over sitting inside.