Neither of them are good, partly due to the design and partly due to iPadOS. Nevertheless, if you are determined to get one, then the Magic Keyboard.

Designed to fail. Both the Magic Keyboard and the Smart Keyboard Folio requires physical connections with the gold contacts on the back of the iPad; to do that, there is a ribbon cable embedded in their hinges. The Magic Keyboard hinge is metal, much like that on a normal laptop; so there is nothing wrong there. On the other hand, then Smart Keyboard Folio hinge is a flexible piece of rubber/fabric. This means that as you open and close the folio, the copper traces in the in the hinge would get folded and eventually fatigued break. My Smart Keyboard Folio start losing connections after 1.5 years and would required me to hold it in certain ways to register. It completely loss all keyboard functionality after the second year.

Magic Keyboard does not have the aforementioned design flaw. However, as the hinge is similar to that as a laptop, you cannot just gently open it to check notification (or something like that) like a normal tablet. It needs to be open with intent. Also, you will also need to decide on how often (or if) you want to use the Apple Pencil. As the iPad needs to be remove from the Magic Keyboard for usages with the pencil. However, the camera bump is huge and it will cause the tablet to rock around as you write on it without a case. My only solution for this, so far, is to flip the iPad upside-down and have the camera bump dangle off the table edge while writing.

The software is not there yet (or it may never be). The key problem is that this is not entirely Apple’s fault, but they are responsible for a lot of it. Most apps are not built with the physical keyboard in mind. Therefore, the UI can sometime glitch-out with the keyboards attached. This goes on both of them. In addition, the spacebar often just acted as “select” rather than a “space”. This means that you would sometime select whatever button on the top left of app (like the “Back” button in a browser), rather than inserting a “space” into whatever text field you are typing in. The work-around here is to use Option+Space instead.

Overall, I had bought into the iPad-as-a-laptop-replacement idea in 2018 (literally), and I am very disappointed. If you want to buy some accessories for an iPad, then I suggest the Apple Pencil and whichever cover on Amazon that fit your taste/needs. The keyboard and cursor experiences on the iPad is usable; but, it does not worth $150/$300. If you need a keyboard, get a real computer.