I see the appeal of trying to upgrade to F on BA. If it looks like you can do that, BA wins. Otherwise, CX is better in terms of IFE, service and seat, unless you're quite large. I'm 6'2" and 210 lbs and like it a lot, but some folks as big or bigger than me might find it a squeeze.

If by some chance you can get the new CX J, the calculation might chance. In that case, I'd save my miles for the BA F upgrade and stick with CX.