I like what you say, Ovarwa. Hope you don't mind me responding to two things that weren't your main point:
(eg: get the drop using Assassin, quicken and twin a melee cantrip using Sorcerer, and then action surge to do that again in your first round.... or grab all the skills&cantrips using lots of dips...)
[snip]
Or to divert from a beeline to Paladin6 and one of the very best abilities in the game? (Getting a few points of dpr for one character feels good, but adding +3 or +4 to everyone's saving throws breaks Bounded Accuracy in your favor!)
1.)
Nitpick: Action Surge doesn't let you Quicken + Twin a second cantrip. You get another action, not another bonus action + action. Fighter/Assassin/Sorcs FYI.
2.) RE: Paladin saves, it's not breaking bounded accuracy, because bounded accuracy is a DM-side philosophy. Rodney Thompson invented bounded accuracy, and the way he described it was (emphasis added):
http://bluishcertainty.blogspot.com/2016/06/bounded-accuracy.html said:
The basic premise behind the bounded accuracy system is simple: we make no assumptions on the DM's side of the game that the player's attack and spell accuracy, or their defenses, increase as a result of gaining levels. Instead, we represent the difference in characters of various levels primarily through their hit points, the amount of damage they deal, and the various new abilities they have gained. Characters can fight tougher monsters not because they can finally hit them, but because their damage is sufficient to take a significant chunk out of the monster's hit points; likewise, the character can now stand up to a few hits from that monster without being killed easily, thanks to the character's increased hit points. Furthermore, gaining levels grants the characters new capabilities, which go much farther toward making your character feel different than simple numerical increases.
Now, note that I said that we make no assumptions on the DM's side of the game about increased accuracy and defenses. This does not mean that the players do not gain bonuses to accuracy and defenses. It does mean, however, that we do not need to make sure that characters advance on a set schedule, and we can let each class advance at its own appropriate pace. Thus, wizards don't have to gain a +10 bonus to weapon attack rolls just for reaching a higher level in order to keep participating; if wizards never gain an accuracy bonus, they can still contribute just fine to the ongoing play experience.
When the Paladin gives his buddies a save bonus, it doesn't really break bounded accuracy at all. He's just doing what he's intended to do.
Also, in practice I find that there's a pretty severe limitation to the Paladin's aura: the party has to all clump up next to the paladin. If you're fighting a dragon, you can
either huddle next to the paladin to make both of you (all four/five of you?) a more tempting target with slightly higher saving Dex saves; or you can scatter so that the dragon's breath weapon would only hit one or two PCs. Same thing applies to mind flayers, magma mephits, Flameskulls, and even basilisks and medusas. It's nice to have the Paladin's aura on tap just in case you get into a close-quarters battle, but not having to make a saving throw at all beats making a saving throw at a +5 bonus.
So in practice I have seen the Paladin's aura be best at two things: protecting the paladin himself and maybe one other vulnerable PC on the front line; and making the paladin more resilient to friendly fire. E.g. a Paladin of Devotion 7+ can simply ignore Hypnotic Pattern because it's a charm effect, and that's kind of neat for close-quarters tanking against a mob of cranium rats or orcs or umber hulks/whatnot.
But despite its shortcomings, I agree that the Paladin's aura is one of the most desirable abilities in the game. Arguably Bardic Inspiration is tactically "better" in a pinch, but the Paladin aura is more attractive emotionally because it's always on and more reliable. It's a good security blanket.