the tamron is probably sharper stopped down beyond f8 than the nikon 105vr. the tamrons AF is noisy and it also extends to double its physical length when focusing at minimum distance.
vr is no big deal as it is not very effective at macro distances, in fact the four extra glass elements in the vr lens may induce ca slightly.
i have owned and used the tamron and 105mm micro nikkor af-d {non vr}. ..... i sold the tamron in favour of the micro nikkor.