The Shield and Hex comments weren't for the AT, just to clarify. One or the other is great for the bard, EK, and ranger because normally one of those is inaccessible and they're stat-independent.
If something costs you a feat, there's an opportunity cost because of any other feat available. An early feat choice needs to be something that's useful at all levels that won't diminish in usefulness as the character grows. I don't see the appeal in Faerie Fire so much for an AT at all levels. It's fine for low levels when the AT doesn't have so many spells to use, but when 3rd level spells are available, I'd rather have a reliable Hypnotic Pattern if I'm going to cast an area spell. The stat spread needed to make a Faerie Fire package work is undesirable for long-term play IMO. You won't have ASIs to split between Dex, Int, and Wis in most scenarios, and long-term you're giving up the reliability of higher level AT spells just to make Faerie Fire work.
Bless on the other hand is ability-score-independent, so that's a great pick without sacrificing any functionality at later levels. Not trying to dilute your argument here, but I do want to point out as a DM of multiple games that have gone to or are currently in high levels, it's a mistake for a cleric to forget about using Bless at high levels. Druids are bogged down by a list that has too many concentration spells, and bards do indeed have better things to concentrate on than Faerie Fire. Clerics have good non-concentration spells and Bless is one of the best buffs on their class list. They can get away with novas in some fights because their low level concentration stuff can carry them so far.
Lack of reliability on Sneak Attack is a problem for rogues that forget that ranged attacks work for Sneak Attack. Hiding for the advantage granted by attacking unseen plus a ranged attack on the first turn is a pretty reliable way to Sneak Attack, and remaining at range makes Cunning Action to hide a lot more viable for repeated use in combat. Shortbows and light crossbows don't get much talk, but an 80 ft. range Sneak Attack is enough to make one a worthwhile choice for a backup weapon on a melee-focused AT as opposed to trying to make Sacred Flame work. I'm not accusing you of doing so, but it seems the online community as a whole forgot ATs can Sneak Attack from range just because Booming Blade and Green-Flame Blade offer them a higher damage Sneak Attack.
Off on a tanget, the 13th level AT ability is totally overrated and it shows in most online discussion. Most discussion seems to assume the AT has Mage Hand out and in position 24/7. If one actually tracks the movement and duration of the hand, it's not 100% reliable. RAW, gaining advantage via Versatile Trickster is not one of the uses on Mage Hand that allows it to move and the feature provides no wording to allow the hand to move. Performing an action with the hand in order to move it is an action or a bonus action for the AT, so unless the hand is already in position, the AT won't gain advantage from the hand and attack/cast in the same turn. I have not seen any tweets or anything in the Sage Advice Compendium to clarify RAI yet.
Shield as an MI spell does allow the AT to take Find Familiar with its off-school 1st level spell. (I prefer that order because an extra use of Shield is more often useful than an extra use of Find Familiar.) MI: wizard is a decent alternative to taking Ritual Caster because of the extra cantrips. Extra cantrips might not seem that useful, but consider what an AT does with Haste. At 14, the AT can Haste himself, using the Haste action as an extra Cunning Action essentially, or he lands his Sneak Attack with his Haste action and tacks on more damage with a scaled up cantrip via his normal action. A familiar is a good supplement to the Mage Hand tricks because the familiar has its own actions, unlike the hand. An owl's Flyby feature can make it a decent Sneak Attack partner in a pinch, either by flanking or the Help action. RAW, an owl's perception and stealth proficiencies mean it can give the AT advantage for those checks per the Working Together section on page 175, though a DM could invoke the "no easier with help" clause.
