Some of the features to consider (by no means exhaustive):
1. Width: 60%, TKL, or full-size
2. Height: Normal or low-profile
3. Key layout: Ergonomic, ortho, staggered
4. OS-friendly layout: Mac or Windows
5. Switches: clicky, tactile, linear
6. Misc: RGB, programmable keys, wireless
Personally I like 60% low-profile clicky keyboards. I use a Keychron K7 at home and MX Keys Mini at work.