In Baldur's Gate 3, the last-selected class during leveling up determines your spellcasting modifier attribute - one of the reasons why I usually only multiclass during respeccing, unless I'm combining classes that don't cast spells at all.
With the strong overlap between Sorcerers and Wizards (back in my 3.5 days, they used to have the exact same spell list), I've already seen builds for Sorcerers that cast all their spells with intelligence by picking Wizard levels last.
I've tried to find that video on YouTube again but couldn't at the moment (it's from the guy who always has notes in black-on-white editor text on the right side of the screen, but I've forgotten his name). He explained some upside to using intelligence as the spellcasting attribute (overall, it's a less useful attribute than charisma; I think that's hardly debatable, since I don't know of any noteworthy conversation skill checks with other NPCs requiring intelligence).
So conversely, I now asked myself if charisma might be the better spellcasting modifier for Wizards, too? Rather than investing a bunch of skill points into intelligence, always ending on a Sorcerer or Warlock level would allow you to play a charismatic but unintelligent wizard instead. This might lend itself especially well to melee casters, as one of the most powerful Wizard builds is the Abjuration Wizard with Armour of Agathys. This Wizard wants to be in melee, ideally provoking opportunity attacks left and right, constantly dealing damage with Armour of Agathys while Arcane Ward prevents the Wizard from taking any damage himself.
Analogously to my recent question "Who is your thrower: Karlach or Lae'zel?", this then leads to the question:
Who is your preferred melee caster: Gale or Wyll?Lore-wise, Wyll obviously wants to do melee combat - so desperately that he jumps off his advantageous high ground at the Emerald Grove, just to stab a goblin with his blade. But as a Warlock, a lot of people won't let him do that, because why would you if you could just hide him in a Darkness cloud and start Eldritch-Blasting away? The primary argument for the alternative is Booming Blade -
pact weapons alone wouldn't convince me to send Wyll into Melee, especially not with Light Armour only.The melee Wizard, meanwhile - presumably Gale - takes little to no damage in melee if he specialises in Abjuration. But in turn, he can only do damage passively, by provoking opportunity attacks into his Armour of Agathys (for which he has to multiclass anyway, preferrably into Draconic Bloodline: White Sorcerer, rather than into Warlock). There isn't really a good melee damage spell for Wizards, like Inflict Wounds for Clerics. And if you want to use Inflict Wounds as a Wizard Cleric multiclass, you'll likely make the Wizard a Necromancer, not an Abjuration Wizard.
The best spell a Wizard could cast in melee is probably Shocking Grasp, but only if you're abusing the Wet condition anyway, given that Armour of Agathys deals cold damage. And are you really playing a Wizard to cast only cantrips?
That feels very much like playing a Warlock... =D (Admittedly, Ice Sorcerers eventually end up only wanting to cast Ray of Frost.)
It would make sense to me to give the Wizard who already has a single Draconic-Bloodline Sorcerer level for Armour of Agathys a single level in Hexblade (duh) for Booming Blade. But at that point at latest, picking the Sorcerer or Warlock level last and thereby making the Wizard cast everything with charisma seems like the obvious way to go? Because you kind of need a pact weapon / some way to add your spellcasting modifier to your weapon attack roll to make Booming Blade good, if you're not a martial class. So that begs for a level in Warlock, and for casting everything with charisma, even if the majority of your levels are in Wizard. Especially because you could now add Paladin levels for even more melee damage, while you're at it.
Adding Paladin levels in turn makes more sense with Wyll, lore- and personality-wise.
I guess the question is being made more complicated by the fact that Gale doesn't really have a canonical subclass: By default, he picks Evocation (probably just to easy beginners into the game); in one dialogue, he says he prefers Abjuration to something else another companion suggests; and if you make him a professor, he ends up specialising in Illusion.
