I paxed on Arik Air's A340-500 from Lagos to Heathrow, just before Christmas... and all I can say is "WOW!".
The seat pitch throughout economy was excellent. The seats themselves were very comfy (
'Recaro', if I recall correctly?), all with seat-back entertainment systems.
Business / 1st class was equally as good as what you get on some well known Middle East carriers.
The onboard service was great. Good meals. Free drinks and the two (yes, 2) onboard bars (
which we made good use of) are perfect for enjoying several hours chatting & drinking with ones mates in a manner which might best be described as a very smart flying wine bar.
Bottom line is that the whole aircraft and the onboard service knocks what I experienced with Virgin Nigeria (
on the southbound sector, two weeks prior) into a cocked hat and some!
BA, VK, VS.... might I politely suggest that, to commpete with Arik, you'll need to seriously up your game on the London-Lagos route!