I like 11 levels in Sorcerer with 1 lvl in any other class.
Each Sorcerer sub-class seems pretty solid. WIld Magic you get tides of Chaos which has the sorcery coasting through most checks. Draconic Sorcery you get the Lineage elemental perks, scale AC and draconic flight. Storm Sorcery you get Tempestuous flight, and all the thunder and lightning themed angles.
This last is pretty fun with a dip in any caster class that can take the ritual transmutation spell Longstrider at lvl 1. Casting it counts as a levelled spell, but without the cost to the slot. You can Tempestuously Fly whenever, as soon as you learn that one from the Multi-Class. Works with the other ritual spells as well, like find Familiar say, but Longstrider doesn't have any per long/short rest requirements, so you can cast that one at will.
Wizard is a pretty OP combo for cross caster Sorcerer multi, mainly because you can still stay on pace at the high end for arcane spell progression. Your known sorcerer spells (chosen at level up) will still be 1 lvl off the standard power spikes, but because you unlock the Sorcerer spellslots you can write the spell as a Wizard (least up to lvl 5 spells). So for example, lvl 1 Wizard/4 Sorcerer, can write the spell Haste and cast it using the lvl 3 sorcerer spellslot achieved at character lvl 5. They'll get to choose the Sorcerer lvl 3 spell at the next character level 6 (1 Wiz/5 sorcerer) but until then you can still punch above your weight and write/caste from the top slots as a Wizard. Some spells work better for this, like say summons, buffs or spells that usually always hit, then save the more finicky direct damage, CC or disabling type spells for the higher CHA rolls from known Sorcerer spells at the next lvl up. Even using INT for writing above level that way, you can still do alright because the Circlet of Intellect is available very early on. But yeah, you get to do all the Wizardy things with the innate power and gift of gab that a Sorcerer gets, including all the Meta Magic. Both dialogue options are nice, since the Sorcerer dialogue tends to be saltier and snarkier, Wizard more subdued, so a bit more room to RP either angle.
After that, I like any of the other dips into Full Caster classes along with 11 lvls in Sorcerer. If they have a lvl 1 spell list with stuff that can be upcast, twinned, distanced, quickened etc that's always kinda fun to tease out. With a Cleric dip you get to choose a deity and a domain perk, along with whatever weapons or armor proficiencies from the subclass. With Bard you get to be more of a skill jockey along with Tasha's and whatnot. Warlock is the most complicated combo, because they have a different way of gaining spellslots from all the other casters, allowing them to eat spellslots to replenish Sorcery points on Short Rest, but the way the game is set up this is more awkward to execute than it might seem, since it defaults to Sorcery Spellslots for the Sorcery point conversion. Basically you'll have to eat the Warlocks slots last in sequence, when most would probably want to eat those Warlock slots first since the whole point is to push the Short Rest to double up.
I wish Jack of All Trades was worded somewhat differently. For the same reason that I like to focus on Party Composition with an eye towards the total number of party comps available, there are many more potential builds for a Triple Class Character or Quad Class Character, than there are with taking a single level in all 12 classes available. There are no interesting splits or decisions to make except regarding which Class to take first or to prioritize in sequence. I think a potentially cool concept might have been something like pick 6 out of a dozen. But then I'm always saying that, with just about everything in BG3 lol.
