I've done both, and really enjoyed the upper deck of the 747-200 (a few years back, when it was still flying to Europe). Old style WBC, "barcalounger" seats, with a lot room, storage, etc. I believe they all have the new WBC seats now, better IFE, etc.

On the other hand, I like the A330, but it doesn't seem as roomy to me. I also have a hard time getting comfortable in the new WBC seats, even though they're very adjustable. They're a little narrower and not nearly as "cushy", kind of like sitting on upholstered cardboard. YMMV