Em D
After maybe three or four hours of practicing just moving between E minor and D on the guitar, I managed to be able to switch between these two chords.
It's amazing how much practice it takes to get one's fingers to get them to do what you want them to do.
And I'm not even hitting them 100% of the time... so much time... but I think it's good to keep my brain malleable enough to keep learning new things.
All of this is learning through Guitar Tricks... so far I think it's going well.