I suppose my only thought would be that the BA flight would be two long haul aircraft and therefore more comfortable compared to the 320 you are likely to get on the second leg of the EY route. Reckon the EY service to be better (assuming you're flying Y from the comment on prices) if your are flying J then the Etihad product, in my opinion, is considerably better.

Maybe take into account the break in the middle of your journey at LHR rather than one incredibly long flight and then a hop.

Have a nice flight !