I don't like 14mm on Milky Way... its too tiny without good resolution for stars.Please Canon, an astrophotography capable RF lens to compete with the Sigma 14mm f/1.8. This lens isn't quite wide enough for optimal nightscape shooting IMHO.
I think 35mm is a good compromise, but you have to use tracking. But you get far better details.
Its the EF 35 IS, but it has coma with 2.0 too, so i have to use f/3.5. But then its very good. And I use this lens for much other photos too, its not a one-trick-pony like a 14mm 1.8... But your option might be another... no problem.