I would just like to note, by the way, that I love how this thread has evolved, and I'm really enjoying hearing what the two of you as very experienced, knowledgeable, and articulate commenters have to say about all of this. I'm trying to mostly sit back and take it in since, frankly, I don't have anywhere near the time on the ground (or, at the table) that you two have, so most of what I can contribute is based on armchair analysis.
What a Valor Bard is, and what they excel at, is casting. They are a caster, like your party sorcerer, except they have more skills, JOAT, Inspiration, and a good AC.
Now, it's easy to assume the Lore Bard is signficantly better at casting, after all, magical secrets at level 6 right? I mean fireball? Shield?
Here's the thing though, at level 5 is when the Bard spell list really comes into its own.
Best level 3 combat spell in the game: Hypnotic Pattern (You lore bards that waste your 3rd level slots on fireball make me sad)
Best level 4 combat spell in the game: Polymorph
Best level 5 combat spell in the game: Animate objects
and shield? If you had half-plate and a real shield, you wouldn't need shield in the first place.
Interesting perspective. Definitely counterintuitive to think of the valor bard as coming out on top on a caster-to-caster comparison. I'm not fully sold, but you make a strong case!
Totally agree re: fireball. I can imagine party compositions where you might take it, but if straight damage is that high a priority, why are you a bard? If you're spending magical secrets on shield and fireball, you're playing catch up, not leaning in to what a lore bard can be. Agree even more so about swift quiver. It's a nice boost, but doesn't in any way seem like something you'd organize a whole build around, or even something that's worth spending a 5th level slot on, compared to other things you could be casting at that level. Even if all you're interested in is damage, animate objects gives you way more of it per turn than two measly arrow shots.
If you're going to spend a magical secrets pick on self-protection (which I'm not sure seems like a good move), it feels to me like mirror image is a better choice than shield as a lore bard. Yes, it's a higher level slot, but unless you're taking a lot of attacks in a round (which, as a lore bard, probably means you or your party have done something wrong, no?), it's likely to give you stronger protection, from more attacks, without competing for your reaction (so you can stack cutting words on top of it if needed). Would you agree? On the other hand, if you're staying out of the fray like you should be doing as a lore bard, maybe you hope that you need that spell less than once per combat encounter on average, in which case you'd rather use the spell slot reactively than have to use it prospectively.
As to the cutting words vs. combat inspiration comparison, it seems like you're trading one type of flexibility for another. I think it's clear that combat inspiration gives you a more useful set of options, largely because you can simply give out the die and then the user can as needed use it as either regular bardic inspiration or on a damage roll / AC boost. That's not something I'd fully considered, honestly. And it's not necessarily limited to one use per round, provided you have enough warning to hand it out ahead of time.
On the other hand, if the distribution of important borderline attack rolls is concentrated on a particular character, rather than in a particular round, it seems like cutting words makes it more likely than you can allocate your inspirations optimally (instead of handing out one to each character). As far as the ability check use, it does seem a lot more situational, although it's also difficult for me to imagine, even with 15 inspiration uses per day, that using combat inspiration to bump damage in place of on an attack roll is going to get used that often, since unless you can use it so liberally that there just aren't enough attacks in a day that are within spitting distance of hitting, going from zero to one attack's worth of damage should usually be more valuable than 1dX worth of damage, level for level. At least assuming you're using your inspiration on a character with reasonably powerful attacks for the level.
As to the reaction use, both the combat inspiration AC boost and cutting words use a reaction, it's just that one uses yours and the other uses the character's reaction who's getting hit. My intuition is that more often than not, the players getting hit more are going to have more competition for their reactions, or at least, place more value on threatening something with a possible reaction. If you hand combat inspiration to your fighter and they use it to make an attack miss them, now whoever is engaged with them basically now has a free disengage if they want it. Moreover, frontline types often have class abilities that use reactions, for example protection style or riposte maneuver for a fighter). Whereas if you do the same thing with cutting words, it's your reaction, and you're probably not threatening many AoOs.
In my limited experience so far, what I've found is that I can often give one person inspiration before combat starts, but there is usually not enough warning that a battle is coming in the next, say, 9 in-game minutes (let alone knowing that it's a battle that will merit a use of inspiration, though that gets easier after level 5, and I'm not there yet) for more than one turn's worth of action. It might be that I could be more efficient about this, but it does feel so far that being able to pick and choose spots on the spot is a boon.
Again, I'm not really speaking from much experience, so grain of salt with all of this.
