Sigma 100 300
 

I have just purchased the Sigma 200 300. and will use it only for birding. I looked at the three lenes you mention and almost got the Nikon 300 but decided I needed the flexibility of the zoom. On my D70 it focuses fast and quietly. It is however a bid lens and requires a monopod at least. I have hand held a few shots as like in flight pics but it is challenging and will be more so with the TC. I have also found the AF difficult in very flat light such as morning mists where a final manual focus is best.

good Luck