There was a similar discussion recently here. I assume you're talking about the newer VC Tamron 70-200 if you're considering the nikon as well. I ended up going for the tamron it's an awesome lens the iq is pretty much there with the nikon VRII, For me it's perfect but it doesn't have any teleconvertors so if your thinking of using it longer than 200 you want the nikon. I also find whilst the VC is awesome for portraits and stills it can be a bit grippy with tracking My experience of Nikon VR is better for this and offers the extra active mode. If you're shooting sports or wildlife I'd go Nikon for those features but for general shooting or portraiture the Tamron is hard to match for the price. I got mine used for a little under £650 used so a lot cheaper than either Nikon and for my use it's excellent.
When i shot pro i had a Nikon VRII, nothing can touch it, when i quit and became just another hobbyist i bought the Tamron VC but soon realised that for my requirements i had wasted my money as it couldn't take TC's including Kenkosdammit
using a teleconverter was quite important to me as I wanted the lens to double up into a zoom lens.
hmm
Im gonna be investing in a tokina 12-24 and just need a lens which i can sort of master long range shots
dammit
using a teleconverter was quite important to me as I wanted the lens to double up into a zoom lens.
hmm
thanks guys for the valuable advice. Money isn't really an issue but obviously would like to spend less.
Problem with the 300mm prime is its too fixed
This...If money isn't an issue then the choice is clear - Nikon.
Thing is, if you go for another brand, you'll always have that "nagging" feeling that you missing out on something.