[JJ_SO]

Do it for your own pleasure... so far, I never missed a feature or found a function which was working on a Nikkor lens, but not on a Sigma or Tamron. I'm not saying there are not such lenses. I'm just saying, if I have or had them, I didn't notice any super-secret extra cool gadgets. 

 

On the contrary!

 

Tamron:

• All lens collars come with Arca-swallow tail.
  
• The lenses are very well designed, with metal parts at the spots for the collar
  
• 100-400: I've never seen this feature to choose either a dedicated distance zone OR choose a distance limit and the zone results from the position of the focus ring when switching it ON. How cool's that?
  
• Tap-in console for future firmware updates, customisations like sensitivity for override manual focus
  

Sigma:

• USB dock, same purpose as Tamron's tap-in console
  
• lens foot (of 150-600 Sports or 500/4 Sports) as an option, very long and again with Arca profile
  
• better rear lens caps than Nikon has
  
• Mount change service - if you ever get attracted to Canon...
  
• Some lenses are very unique and not available from Nikon or if, then the Sigma's are often delivering better IQ
  

Nikon:

• lately some price increases of next generation lenses which really hurt (12k for a 180-400/4 zoom, which was before half price), and I don't see these prices backed up by raising IQ.
  
• The105/1.4 G is also very unique, but for that price I could get a Sigma 135/1.8 AND  85/1.4 Art...
  
• if lens collars, I only know extremeley wobbly design (300/4 PF E, 70-200/4 G)
  
• However, the 300/4 PF E was worth the puchase. In it's range it's the lightest 300 mm I can get.
  
• the rear caps suck
  
• the front case easily flip out of the fingers