Great question. I have both. I love my Kopykake I can count on it, I am used to using it and I can sit at it for hours if I need to. But I have to have my designs ready or printed out. On the other hand, it takes up space and any major designs adjustments send me back to my computer to print out a new image.
I recently bought a Pico. I like it too, but for different reasons. first it is small and portable. I could easily take it to a friends house to use. You still need space when using it, but when done, you can put it away, it is so small. That may seem great, but it also means that then I have to set it up each time I want to use it. ( this sounds minor, but there are so many times I just flip on the Kopycake for a quick line or circle and all those mini minutes of set up add up.) I love the sizing ability on the Pico. I use it with my Ipad and the Camera Lucida app. This app had great artistic features for our craft!
Here are the downsides. Yes you can use it in the middle of you kitchen table with your Ipad and not need electricity. (If the battery is charged) but when the battery charge runs out you need to plug in if your project is not done. So I was working on a big order, the projector died after 2 1/2 hours, then my Ipad died, so then I had a power strip running across my kitchen to charge both devices in order to finish my LARGE project. I was in cable misery!!
When I bought the PICO I was going to sell my kopykake, but I really think I am going to keep both. Crazy!!! They are both great in different ways. If I had to pick just one. I would pick the PICO for cost reasons.