Turbine Kiwi, Don't think you'll have much of a choice, it seems as if most of the new hires are being placed on to the 777. If you are sure this is the place you want to be take whatever gets you here the quickest.
I wanted a Bus gig so I could get back to NZ and Aus, but am on the 744 instead. Every fleet has is advantages and disadvantages. I'm not flying yet, still going thru all the hoops.
From how I see it
Bus; great variation, good guys, some extended layovers. Disadvantage being CCQ'd means working harder.
777; young fleet SO are only doing Bahrains and NYC at the moment, but will get progressively more destination. By the sounds of it most guys in the near future will upgrade on to the 777.
747; Daddy's yacht! A classic. Still a good network with a variation of Europe and America. As it is Long Haul, no quick trips to make up your flight hours like the A330. Perhaps this means more time off compared to Bus ccq'd crews.
This is what I make of it and don't guaranttee any info. As I said still new and trying to sort it all out myself. If you want any more info you can message me privately. I left NZ only a few months ago.