If I were designing 5e from the ground up, I'd have gone:
* Str saves - Entangle effects, forced movement, telekinesis
* Dex saves - explosions and things to dodge
* Con saves - poisons, body alteration, things that would fatigue like heat or cold
* Int saves - illusions, memory alteration (you figure out that something's not right)
* Wis saves - psychic damage, charm, fear and other emotions (you find serenity, are resilient against harm, and recognize deception)
* Cha saves - compulsion, mind control, and possession (your sense of identity pushes back against direct control)