ECONOMY CLASS
If Aer Lingus you benefit from the 2 - 4 - 2 seating providing you can obtain one of the two seats on the A330, so a little bit more space.
Though BA in economy on the A380 on the upper deck at the back has 2 - 4 - 2 seating in economy also.
I think they are almost on Par in economy.
PREMIUM ECONOMY
only an option with BA
BUSINESS CLASS
For this I would personally pick Aer Lingus for the Thomson Vantage seat, which I think is now installed on all the A330's though I could be mistaken.