I know you absolutely love Evard's since 3.5 (where it was really overpowered). But I would like to ask: Is the 3d6 damage really worth the two spell slots? It seems like web is very similar. Web allows only a strength check, not str or dex to get free and lightly obscures. It does need anchor points though. In my opinion Web is the overall better control spell and may deserve a sky blue rating. I'm not so sure spending a 4th level slot to add 3d6 damage to restrained creatures who might have an easier time getting out is worth it.
As Hemlock mentions, we are likely looking at more than 3d6 damage, however, I still agree with your point. I will consider both these spells, I've likely overrated Evard's, as I've failed to get the milage from it that I originally expected. I do think that the anchor point limitation isn't as bad as it once was (as you can now "layer" the web), but it isn't good enough for blue rating. I've downgraded Evard's to green. They are both good spells, but neither are standouts IMO.
About Otiluke's Resilient Sphere:
This spell seems really good in a vacuum because it is so versatile.
This statement seems odd to me. I usually consider circumstantial spells to be better in a vacuum. Versatility is usually better in actual play.
But as an actual Wizard, you may want to cast polymorph instead if you need to save an ally. It seems like a much better proposition in general.
I agree here - not because Otiluke's isn't good for this purpose, but because Polymorph is SO good for this purpose. Keep in mind though that it's hard for even other blue spells to compare well for their level to Polymorph, which may well be the best spell for its level in the game...scratch that. It is clearly the best spell for its level in the game. At level 7 you can turn your buddy into a giant ape - 157 hp and 2 attacks at +9 for 22 hp damage each. That's out of control good. If you are trying to convince me that Polymorph is better than Otiluke's, you are preaching to the choir.
You may also want to use other spells if your aim is to remove an opponent from combat. Using the sphere for that purpose seems like a bad idea, the same way you really dislike single target save or suck.
I am not a huge fan of single target save or suck (as it is an all-or-nothing proposition), and if that was the only use of the spell, I would be much less enthused with it. Keep in mind though there is more than one use. From a defensive standpoint, there are circumstances where it is better than Polymorph (particularly in self-defense). In regards to trapping an enemy, it's OK. Much better than single target save or sucks that provide a saving throw every round.
If you really must have a save or suck spell, maybe something targeting an unusual save (Banishment/Phantasmal Force) or lower level (Tasha's) would be a better use of your spell slots.
So we're comparing spells that do different things here, but there's a bit of apples and oranges going on here, but in all cases, I think Otiluke's holds it's own. Let me go through:
Banishment: First off, this is a good spell - in fact, I rate Banishment the same as Otiluke's. Banishment has the advantage of better save target, better versatility of targets, but lacks the defensive uses of Otiluke's. Overall - similar spells in value.
Phantasmal Force: Obviously, we have some targeting issues with spells that don't impact undead, but in addition, you can get a saving throw every round against Phantasmal force. Single target spell with saving throw every round...I was just mentioning that. In order for this spell to have the staying power of Otiluke's the enemy has to fail 10 saves in a row. Naturally of course, it also lacks the versatility, as does banishment. The difference in power between this an Otiluke's is pretty striking.
Tasha's: I love Tasha's, because it's pretty effective for a 1st level spell - but it is the ultimate single target save every round spell. This spell is really uncomparable to Otiluke's, as one would expect comparing 1st level to 4th level spells.
dOn paper, the spell looks really tempting but when I think about what I would use it for, I find I already memorised other spells doing the same job but better.
I'll take a memorized Polymorph and a memorized Banishment over a memorized Otiluke's
If there was no limit on preparations. I don't think you are considering the value of spells that provide multiple functions. As you level up, determining which spells are prepared becomes ever more challenging. If you can perform multiple functions with one spell (even if each function is less dramatic than a single-purpose spell), this has signficant value.
I know there has already been some discussion about Phantasmal Force but if you rate Banishment green for targeting an unusual save and Otiluke's for it's versatility as save or suck, Phantasmal Force deserves a green rating too imho
Single target save or suck with a save every round that several creatures are immune to. I'm satisfied with its rating.
Edit: I needed to add the "if there was no limit on preparations" for clarity