E/2

Enthrall

This is basically "Bullshit: The Spell". On casting you let out a string of gibberish that your target, if they fail a save, and you get to have advantage for one minute or "Concentration". I dunno, maybe I'm getting jaded already, but this seems like something you could replicate just by telling a story about a dream you once had.

Real-World Rating: 3 (Pretty Ineffectual)

Etherealness

The rare example of a spell that's vastly more effective in the 'real world' than in D&D, Etherealness lets you basically turn into a living ghost -- invisible, intangible, and able to go anywhere and see anything -- for eight hours. In the game, this is fraught with peril, as you are still subject to spells, ethereal beings, and other risks, but in our reality, it's basically a ticket to omniscience. You don't get it until seventh level, but it's worth it!  Basically beats almost any kind of divination spell there is.

Real-World Rating:  10 (Essential)

Evard's Black Tentacles

I forget which buddy of Gygax's Evard was named after, but it was for sure one of his midwest libertarian drinking buddies, so he got himself a cutesy nickname and a spell that no doubt causes fans of shokushu goukan to get all bothered in the loins. In practical terms, it's more or less a version of Entangle that causes more damage and is gross, which means it is more effective in freaking people out than it is doing its actual job, but it's fine on its own merits. My one note is that the material component is a giant squid tentacle, which, who carries a giant squid tentacle around with them just in case you need to tie someone up? 

Real-World Rating: 6 (Pretty Okay)

Expeditious Retreat

I'm gonna be straight here: I love the hell out of this spell. I love that it's a low-level spell that actually does something useful; I love the name; and I love that they have such a complicated concept around the idea of "I'm running the hell away as fast as possible". It's probably less effective overall than just stealing a car, but sometimes it's the frills that appeal to you.

Real-World Rating: 7 (Effective)

Eyebite

This used to be a much better spell, predicated on the idea that the concept of biting someone's eye was nausea-inducing. Now it's one of those catch-all spells that does a lot of things, none of them particularly well.

The three things you can do to your targets with this spell by giving them a wizardly thug mug are: (a) make them fall asleep, which you can also do with a Sleep spell five levels lower; (b) make them panic, which you can also do with a Fear spell three levels lower; and (c) make them sick, which just gives them disadvantage and doesn't even guarantee that they'll puke. Once again, you can achieve all these effects with simpler spells or technology, and you won't have to fuck with the possibility you'll throw a 6th-level necromancy away on a lucky saving throw. The name of this spell deserves a better spell.

Real-World Rating: 4 (More Trouble Than It's Worth)