Where to capo for E Dorian
Put the capo at fret 7 and play E Dorian using A Dorian shapes. That is the easiest of the eight positions ranked below, and it is what most players reach for. Against playing E Dorian open, it drops the mean difficulty of the key's seven chords from 3.9 to 3.4 and gains 0 ringing open strings.
You want E. Capo 7 and play in A.
All eight positions, ranked
Each row transposes E Dorian down by that many frets to find the shapes your hand would actually make, then scores the best voicing of all seven chords — fewer fingers, less stretch, closer to the nut, fewer muted strings. Lower is easier. Standard tuning (E2 A2 D3 G3 B3 E4).
What you are playing
The seven chords of E Dorian are Em, F#m, G, A, Bm, C#dim, D — the ones the ranking above is scored against. Their diagrams are on the E Dorian key page.