And which heroes are the best aids for that purpose?
Is PG/Zerk/Ench still good or there are better options nowdays?
My opinion for best base defense IF they have max insight and high lvl enlightenment and skill (other heroes would be better at lower levels):
For aids, same 3 on all defense heroes (again, best case scenario - all with lvl 9 aid skill minimum):
Enchantress is still good, but Pan Goli is fairly worthless for defense aid IMO (but better than nothing). Chiron and Tidal Guardian would also be good aids if needed.