I like the middle seats on the A340s because you never have to climb over anyone and noone ever climbs over you.
Never flown the A333...
The 773 has the same 2-3-2 config as a 747. Then I still like the middle aisle seat because you've got a better chance of not having a neighbor than on a window/window aisle. Furthermore, if you do have a neighbor, there is a chance they are travelling with the other aisle person and will climb over them instead of you.