First off, of all the sites I have visited in the past, I have found this one to have the most insightful commentary. I do not always agree, but people use...reasons. Refreshing.
Anyway, here is my question.
What is "good" at-will damage?
In this we have melee and missile attacks of course but also cantrips and the like.
If possible, provide some sort of cut point (your opinion cannnot be wrong in this) for exceptional at-will damage and poor at-will damage.
If you are really ambitious and want to divide this into martial damage and spell damage as well, I would be thrilled to know your thoughts.
One last moderator is level and tier...good damage at 1st level will of course not be good damage at 15th! In this discussion I think we should dispense with one time effects such as action surges or hasted actions etc. and focus on the at-will component.
I'd say: I'll describe a PC as having "good" damage when they're doing damage competitive with a non-specialized fighter, and when it starts to become cost-effective to improve defense instead: a fighter doing d8+3 or d8+4 per tier has good damage, and so does a warlock without Hex. Someone with excellent damage might do 50% to 100% more than good damage, typically at a cost: e.g. a sorlock quickening Hexed Eldritch Blast is burning his concentration on Hex and sorcery points on every Quickened spell; or a Necromancer might do 10x as much damage as that but with a logistical headache. "Good" is a kind of baseline for me to mentally shoot for when sketching a character build--ideally I'd like all of the PCs in a notional party to have good damage.
Non-melee, non-invocation-boosted cantrips yield what I like to think of as mediocre damage: it gets the job done, slowly. You can kill a were-rat at first level by kiting it using Expeditious Retreat and Chill Touch, but it takes twice as long as if you were a 2nd level Warlock using Agonizing Repelling Blast, which makes you more vulnerable to surprises in the interim if the were-rat turns out not to be the only threat in the area. I like well-rounded notional PCs, so having a PC who can do only mediocre damage leaves me feeling unsatisfied, and I try to avoid it when constructing notional parties.
So:
Vicious Mockery: unusually poor at-will damage, d4 per tier, save-based damage against a generally strong save.
Ray of Frost/Chill Touch: decent/mediocre damage, d8 per tier, attack-based damage with no ability mod. Would probably work fine in play but leaves my constraint-solving instincts unsatisfied--there is often a way to get something better.
Fire Bolt: decent/mediocre damage, d10 per tier on an attack roll.
Monk with a longbow: decent/mediocre damage, d8 plus ability mod, twice per round. Perfectly viable in practice but leaves you functioning primarily as a scout and counterbattery fire instead of a primary ranged combatant; leaves my constraint-solving instincts somewhat regretful that it wasn't possible to do better somehow.
Booming Blade: Good damage, 2d8 per tier, sort of, plus one ability mod, on an attack roll. Enough to satisfy my instincts, at least on a melee off-tank (e.g. Life Cleric 1/Enchanter X).
Thunderclap/Sword Burst: Situationally good damage, d6 per tier per enemy, saved-based damage. Nice to have but wouldn't rely on it as a primary at-will attack; in practice it's easy for this not to be as good as you think it will be even against hordes of orcs.
Agonizing Eldritch Blast: good to excellent damage, d10 per tier with ability mod on an attack roll, plus potential riders that can add 4d4 to 20d6 damage per hit, depending on situation.
Sharpshooter fighter or ranger: generally excellent damage, tends to be 30-50% more damage than a regular fighter, using arrows that cost only 1 gp for twenty.
Necromantic army: fantastic damage on the order of hundreds of points per round even after accounting for hit chances, plus potential for numerous conditions ranging from grappled to hobbled (with caltrops).
When I'm doodling on a napkin with a set of d6s, rolling up PCs for fun to see what they look like, if I can get 3-4 members of a notional 4-man party up to "good" at-will damage, I am happy. Ditto when running solo or computerized 5E games. In my rare times as a tabletop 5E player I'm also pretty happy if I can hit about 10 points of damage per tier without sacrificing utility (as a monk or full spellcaster); or if I do sacrifice utility and play a fighter, I'd want excellent damage (about 15 points of damage per tier) in order to not regret giving up the utility.