You have to make harder choices with the warlock and sorcerer, I think.
To me it's not about hard choices, but the situational nature of many spells. When you're limited like the Warlock and Sorcerer are you'd just never take Illusory Script, and Blight isn't as widely applicable as Banishment or Dimension Door. Even spells like Magic Circle are not nearly as commonly useful as Major Image or Fly. So you never take them. They might as well not be in the game.
But Clerics can pick up rare spells any day of the week when they really need it, and Wizards (with a bit of effort, if it's a must-have for some adventure goal) can track down a scroll and add it to their spell book.
So, for me, I've realized that "full caster" means a full list of spells. Not just all levels, but the full list of whatever spell level you are powerful enough to cast. Or at least potentially, with planning.
This never bothered me for Ranger /Shadow Monk /Eldritch Knight /Etc. because I never considered them real casters. Their magic was just a "magic power" to embellish their primary nature. But for Warlock (at least in my mind), spell casting IS their primary nature. At least for Chain and Tome Warlocks. The Bladelocks are more like Eldritch Knights, so it doesn't bother me as much.
I realize that according to the above logic that a Sorcerer isn't a full caster. But I've never been happy with the Sorcerer for precisely this reason. I have a player with a Sorcerer in my campaign right now, and he's a great character, but he just takes the most generic spells ever. He also overloaded on fire damage and now he's sort of gimped by being in an ancient temple with several fire-immune enemies. Meanwhile the NPC Wizard just swapped out Fireball for Lightning Bolt.
Does being a tome boon warlock change things? At that point you can detect a lot of things and frankly, the warlock can charm and injure as well as anyone else. Choosing fly or invisibility is...a choice.
Yeah, Tome Warlock is a big improvement for me, mainly because of being able to take Rituals from any class.
We will see. I have not gotten a warlock to high level. I suspect trying to be a wizard would not be fully successful.
I think a high-level Warlock has plenty of spellcasting oomf. A dozen+ spells known, 3-4 slots per SR, good high-level Invocations, and of course your Cantrips pump out great damage. My issue, as I mentioned above, is the limitation of being fixed into spell choices for the rest of your character's life. Especially the Mystic Arcanum.