Theres little commonality betwen J claasses in the same way that Y or PE varya lot from airline to airline.
BA biz class is very dated now with the narrow cramped seats- Virgin more spacious but awful beds that only the FAs can work and leave feet projecting into aisle,
EK very nice layout on 380 -cheap tacky decor but good IFE and decent food, on T7 pretty rubbish but then I dont like T7s at all.
Virgin PE is good -better than BA but BA isnt bad as far as the seats go especially if you get the window side pairs.
As for the US side based on recent experiences United on 76s much better than AA which didnt even have built in IFE on their 76 (however my seat mate was the AA check pilot for the flight and a very affable chatty guy who was only too happy to talk about a very interesting Mil and AA career-definately best IFE since the closed FD door days.
As to J class on business well tis easy to say that the 4-5 times multiple cannot be justified bt when you are doing 2-3 long hauls a month plus some intra Europe stuff it really is necessary for your well being and sanity and those FF miles are a justified perk for people who ahve their familly life and marriage impacted by constant absence.
Only ever came across one sensible travel policy and that was years ago, me and my team did 80% of the travelling, it was weekly event for all 6-7 of us -we flew business everyone else flew economy since they seldom did more than once a quarter or even less.
Theres lot more than just nicer food to the J class issue and one has to look at a wide range of issues , as has been pointed out some US companies who enforce these things quite rigidly are oblivious to the Canada= International= Business , NY-Honolulu, 9 hours coach