The problem is that, what I consider to be a good seat layout, width etc. is different to what you will think is good. So consider the hard facts, the web sites of both companies give extensive details about their cabins, seats and features.
I have not done the HKG in BA club for (cranks the brain) January 1991, so cannot say what it is like today! The last time I did the route with VS was in Y (Client would not pay.
However I would agree that, unless you have an overriding factor (cost/FFMs/etc) then either will do the trick. When you have done the trip, please do stop by and tell us your decision and what it was like!