It has to be BA or VS doesn't it? They're streets ahead of the US competition and, while I've never flown long-haul with any of their european competitors, I doubt (and third party stories confirm) that they're sufficiently superior to justify the inconvenience of changing at CDG, AMS, FRA or wherever.
Of course, this latter option may offer better value for money, but then VFM is hard to justify for any biz-class fare. Both BA and VS also have premium economy classes offering much of the extra space that Business Class provides at a price not that far above economy.
The choice between BA and VS comes down (for me) to convenience - timing, frequency etc. I'm sure you'd be very comfortable on either.
You don't say if you have any specific destination(s) in mind - if you're looking at some of the more obscure (ie not Washington or NY), then the availability of a direct flight would swing it for me. If it's really just NYC then the new 'Business Only' carriers such as Maxjet may be of interest. I can't speak from experience of these, since Stansted is too much of a pain for me to get to.