There is no 'best' food - it's all down to what your dog likes and what he/she thrives on.
I've had two dogs who lived very long, happy, healthy lives being fed mainly on Bakers Complete (which is widely sneered at and vilified).
The other two were more tricky - one eventually settled down to pouches of moist food with wholegrain mixer added, the other gets the squits if I ever try to move him away from his Arden Grange Lamb and Rice complete food - so that's what he always gets.
Experiment, see what makes your dog happy and healthy - don't believe the "we know best" brigade - they don't know your individual dog.