In the core 5e rules, there is one pact caster (Warlock) and 5 other full casters (Bard, Cleric, Druid, Sorcerer, Wizard).
Assume, as a hypothetical, you wanted to have 3 pact casters and 3 full casters in your version of the core rules.
What 2 classes of the 5 full casters would you turn into...