Same price so which 70-300 should I get? Tamron or Nikon?

Very mixed responses so I have no solid idea which to choose. Only a few people seem to have owned/tried both and only one person has posted pics and he says those are from the Tamron.

I've tried the Sigma 50-500 and it is very sharp and better contrast than the Nikkor 70-300. But so big.

I still have clear choice, thanks for all the great ideas and opinions yo all who've reied. If the Tamron could duplicate what the Sigma 50-500 can in the smaller package that's what I'll be choosing. If it's just a match for the Nikkor I'll take that as Nikon seems better built, slimmer tube is easier for me to hold, and there's some sealing.

Guess I may have to go and try more of them.