I own both sigma art and ef35/2.
The sigma art is an excellent lens, but is big and heavy.
When I buyed the sigma art I sold the canon, and after an year of usage, I buyed back another copy. Lens are complementary, the canon is less an intimidating lens.
Both nikon 35/2 (i sold it) and 35/1.8 are decent lenses but not excellent. The old is imho sharper in the center and is smaller, the newer has better colors and contrast.
If you aren't worried by sigma size and weight, imho, go to sigma art, is great and not very expensive.
