Sigma 85mm 1.4 vs Nikon 85mm 1.8?

Lookin to get an 85mm. I really want the Sigma for the larger aperture but don't wanna spend all that extra cash if there's not much difference. Can anyone with experience with these two lenses tell me the pros and cons of each?

How long do you expect to keep your lens.

The Nikkor will last for decades. We do not know how long the Sigma will last.

Need to know what body it goes on. The body will determine how it performs ultimately.