It really depends on your perspective. I am a -400 guy. We have 10(11?) ULH departures a day out of HKG 3 are to LA 3(4?) are to LHR and a smattering of others. THat means you will see a lot of LA and LHR!! The pro's of the -400 are that everywhere we go is a daily service so you will have 3 4 day patterns a month, every month. The A340 does several accented 2 or 3 times weekly services giving you the option of some longer layovers.( A buddy of mine has 84 hours in CDG next month) Of course longer layovers means fewer days off, but more beer time at the far end. All in all the rosters are about the same, until... the airbus guys get ccq'd onto the 330 then they go to Australia and DXB. These trips are not worth a lot of hours so the days off count goes down a bit, more choices of layovers, though. The 777 is not here yet so as they come on line they will have few dstinations so not a lot of variety.
As an office, the -400 is set up very well in that we have a toilet and the bunks right in the cockpit. The Airbus guys have to go traipsing about the aircraft for their beds and toilets. I do not know about the layout on the new 777's. The downside of the -400 cockpit is it is noisy and there is no tray table to cut your crew meal.(If you order the lamb curry you will not need a knife)
As far as working environments go, it is probably about the same although a larger percentage of the "colorful" captains described in this forum are on the -400. I do know that the 777 has the reputation of being the funnest fleet in the company.
All in all it doesn't really matter because you will likely change types when you upgrade!
