I’ve flown A350 and B787 on various airlines (e.g. CX, SQ, BA, AA, etc.) and I do prefer the A350 (better than either A380 or B787).
Any of these are a big step up from the B777 or the A330/340 and even from the B747 LD.
However, I’m not sure which I’d pick if it was a choice between A350 or B747 UD :-)