The J seat is the same across all the fleet, although you have the most recent version (called NEV3) on the A380 and not on all B772. But the difference is minor. IFE : basically the same, slightly improved on A380 because they offer a few more movies. The biggest difference is the larger screen on the A380.
So as a whole, the B772 is an excellent aircraft and the A380...a fantastic one. If you can change, I would choose the A380 because it will be a unique experience for you and your family but if you have to stick to to the 772, no big deal