Oh, god, I'd forgotten 4e. And for good reason...I'm not sure I count that thing they called a wizard among the examples from past editions.
You don't have a choice. It was a past edition of D&D. Your prejudice against it does not remove it from it from the record. And, the record shows that casters, even a nominally 'Vancian' wizard (it did prep it's dailies & utilities) can be robustly balanced, effective, and playable with /very few/ daily spell slots. Far fewer than 5e.
I agree with you on the balance of the at-will cantrip vis a vis other casters (like warlock) that makes a lot of sense. Although in practice, given how few spells are rituals, I think the "versatility" of the wizard in practice is maybe a bit overstated.
It's hard to overstate the versatility of neo-Vancian. You can prep a completely different slate of spells each day. You use slots to cast from that list spontaneously. That's far more versatile than a caster that has to choose 'known' spells at chargen & level up, even though such casters are, in turn, far more versatile than non-casters.
Unless you can plan for encounters in advance, the spontaneous system means that, on a typical day, you'll probably have a standard list of spells memorized, making wizards more similar to sorcs in some respects.
That was a strong argument for Sorcerers being 'not that bad' in 3.x, yes - I recall making it many times when defending 3.5 from unwarranted criticism. Of course, it didn't save the Sorcerer from Tier 2 status in the end. It's less valid, now that Sorcerers & Wizards have the same number of slots and cast spontaneously. The 5e wizard's superiority of over the 5e sorcerer is very nearly strict, sorcery points may let the sorcerer save face, but it seems to me the wizard comes out further and more clearly ahead than in 3.5e. (Never mind 4e where both classes were, of course, balanced.)
Granted I think sorcs are screwed in the same way as wizard...I'm not saying we need to return to 4 slots per day at the top eschelon of spells (or was it even 6 for sorcs in 3e?)
At least 6 for sorcerers and 4 for wizards (though it'd take a crazy INT to get bonus spells of very high level). But, because save DCs were based on slot level and damage/level capped by it, it was your top few spell levels that really counted for rocket tag. So, terrible as it was, it's not quite as terrible as a it might sound.
...just that 1 per day at levels 8 and 9, and 2 per day for 6 and 7 are too few.
That's 6 dramatic high-level spells for a 6-8 encounter day, plus all those 5th-and-lower slots, plus at-wills. You can cast 3 spells per encounter, one of them a high (6+) level spell in most (6/8) to all (6/6) of them - some combats probably won't last long enough for you to cast all three. You'll rarely need to resort to a cantrip. How is that not enough? Seems like too much, if anything.
One more at each of these levels would have been helpful (well really boosting all spells per day from 4th on by 1) and I think gotten the balance a bit more right than current.
Balance isn't too high-priority nor precise in 5e, but I doubt it disfavors casters in the least. Either way, it's up to the DM to find the balance the works for his campaign. An easy way to do that without re-writing classes is to vary the number of encounters. More than 6-8 if daily casters tend to dominate (possibly forcing more slots to go towards healing, as well as stretching slots over more encounters), fewer (reversing those effects) if they need a boost.
Now, if we want to talk variants that might be more 'interesting,' I think fewer, but higher level slots could be it. Makes magic more limited, but more dramatic/less commodity-feeling, and, actually, more literally Vancian. (In the Dying Earth, spells didn't have levels, but were merely divided into 'greater' or 'lesser' spells, and capable magicians could memorize about 1.5x as many of the lesser than the greater - personally, I've always thought there was a pretty clear divide between 5th & lower and 6th & higher and would like to see that reflected in the system). It'd be like the current progression, but with your lower level slots 'expiring,' but in return for an extra top level slot. So, instead of 4 slots of each level 5th and lower, and 2 of each 6th & higher, you might have at 6 or 8 level 5 slots and 3 or 4 level 9, only. Fewer spells overall, but more bang per spell.
If you're going to play a 'Vancian' caster, might as well go all the way...
