+1I voted "Other" - the Nikon 300 f/4 AF-S + TC is optically better than any of the zoom options.
I bought this lens with the 1.7 TC used. I'm still improving my monopod technique, with a gripped D300 and TC. I bought a Gitzo 1410 and Kirk BH-1 to go with it. I read Thom's article on support, when you cross the 300mm threshold, having solid support is worth the effort to haul with you.
No experience with the zooms you mentioned. I'm just getting into birding but I've had good luck with 300 shooting wide open doing sports, good IQ.
Good luck with your decision. :smile: