I once promised myself I would never enter this debate...
Ah well.
To say "which is the better aircraft" is a bit like asking "which is the better car" out of a Mercedes or a Porsche.
A great deal of it is down to personal taste, and what you want to do with it. Both make excellent products, both have plus and minus points.
It is a bit fatuous to simply say A is better or B is better, without regard to what you are intending to use it for. Is the A330 better than the 744 on LHR-LAX? Clearly not. Is it better on LGW-LAS? I would say so.
The real answer is therefore - give us a route and let us have a debate on which is the better product on that route.
TA