If I'm flying in PE then the 744 wins hands down compared to the A343 especially on the upper deck - I cannot comment on the A346 though as I've not been on one yet.
If in Upper (J2000) there's not much between the 744 or the A343 - guess there's slightly more space on the 744's (I dont mean actual seat pitch - as that's the same) but more aisle space especially in the nose section. The 744 also has a bigger bar area. The only thing I dont like about the A343 when flying in Upper (I guess the A346 is the same) is everybody boards the aircraft though door 1 (well this has always been the case for me - may be different at different airports) which means everybody has to pass though the upper cabin to get to PE and economy - you cannot relax and read a paper at the bar until you are in flight unlike on the 744's.
Cannot comment on UCS on a 744 yet until after April 18th
