Nikon or Sigma lens, which is better?

Nikon or Sigma lens, which is better?

Sometimes the nikon, sometimes the sigma. With sigma the price/quality tends to be a lot better.

Of course if you're asking questions like this it's extremely unlikely that you already have the skills to make either perform to it's limits in which case this question is moot.

I always presume the original brand is better. Sigma is still a third party lens maker even if it produces its own camera already.

Nikon

Define "better"! There are lots of factors to weigh up:
Better quality images? Nikon BUT would you be able to tell the difference in the real world when you print a 10x8 or view on a budget laptop screen?
Better build quality? Nikon BUT will you use it enough for the difference to show?
Better value for money? Nikon if you are a pro because of greater longevity under harsh useage conditions but if you are a weekend amateur then the Sigma will do the job.
Better kudos? If you want to impress your mates with the flashy expensive badge around your neck then Nikon. If you don't care then Sigma.