[Sirtel]

The Sage is compatible with the Surface Pen (for Microsoft Surface tablets).

I'm not personally familiar with Boox devices, so can't compare them with Kobos. The Libra 2 has an excellent, sharp, clear screen. The Sage is a bit less sharp, but not considerably so. The battery of the Libra lasts for several days to a week to a couple of weeks, depending on the hours of use each day, the frontlight level, wifi being on or not, and to a certain extent on reading speed. In short, it can vary considerably between users, but even in the worst case it should last a few days. The Sage has worse battery life than the Libra, but again that depends on your usage pattern. Mine lasts easily for several days, yours may last less or more.

I have no real complaints about the ergonomics of either the Sage or the Libra 2, and Kobo UI is IMO perfectly fine.