For a Wizard, more spells is pretty much more power, it's their whole thing. Take Fey Touched, you get Misty Step, which you'd definitely want anyway, and an enchantment or divination 1st level spell, say, Silvery Barbs.
You get teleportation and the ability to make an enemy reroll their saving throw against your spell, then have them always prepared to use with spell slots, and a free use for each. Both are useful pretty much through all levels, and allow you to prepare other spells instead, it's two new spells since those two are so good you'd definitely want them annyway.
A Wizard isn't like a Fighter, they don't have one thing they'll always want to do, sometimes damage, sometimes save or suck, sometimes buffing, having more spells gives them more options to use and makes them more powerful overall.
As always, more choices is more power for a Wizard. Say, at-will Mage Armor saves them slots to use on other stuff or Devil's Sight counters the weakness of non darkvision for variant humans, so they don't have to carry stealth-ruining torches or waste a prepared spell and slot on the Darkvision spell.
I was thinking more about Subtle Spell, you can use it twice. Great for casting while not being noticed, or to not be counterspelled if you're fighting another caster.
It definitely ties back to the spell casting power, since it'll save you slots. If you have more AC, they'll hit you less, you'll have to Shield less, and have more spells to cast later. More HP means you survive longer, so if you get attacked there's less chance you'll be KO'd, drop your concentration spells, and, like, die.