Good multiclass combinations with changed spellcasting abilities

[rollingForInit]

What good combinations of classes would exist if you could change the spellcasting abilities of the various classes? For instance, if you could have a Bard or Cleric using Intelligence, or a Sorcrer who used Wisdom. What cool thematic concepts could be realised with it, and what combinations would be good mechanically?

Except Everything 18/Warlock 2 for at will blasting, because that feels obvious.

[MrStabby]

Well if you go down the Dragonborn route of using Con to determine the DC class of spells and effects then I could see classes like barbarian being added to a lot of caster builds. Maybe a Barbarian Valor Bard to get the extra attack? This could be awesome for Eldritch Knights, well in so far as anything could be awesome for them.

If it changed other class abilities as well then there might be some more funky options - Evoker to gain Int damage to Spells + Sorcerer to add (Cha>Int) damage to elemental damage... use the high spell slots for sorcery points to twin/quicken your elemental spells.

How about the slightly more roundabout routes? Respec the wizard to use Con or some other stat then Play a High Elf, taking no levels in Wizard but using the stat of your choice for the cantrip. Magic initiate gets much better if you can respec the class you are taking spells from to use your preferred stat.