Comes down to personal preference.

With the entire trans-atlantic fleet now having Economy Plus, if on a 777 or 767 you get an 18" wide seat, 35" of legroom, and personal television. Many people find that fine for 8-10 hours or so. If on a 747, you'll lose an inch of seat width and PTV.

But for many of us, 30K in miles is a small price to pay for a 19-21" wide seat, 55" of legroom, PTV, and enhanced food and beverage service. Me? I'd consider doing it in Economy on a 767 or 777 if I had a companion, but if by myself, I'm always in Business Class.