Zardnaar
Legend
If we accept the premise that Entangle, Goodberry, medium armor, and shields makes a caster on par with the best level 2 martials wouldn't that lead us to rangers being the best of the best at those levels because they have that too and more?
Bards, sorcerers, and wizards have Sleep for a good spell. Clerics and paladins have Bless for a good spell, and they have solid armor. If having a good spell 2 or 3 times a day is enough then spell casters in general do have that option.
I think low level warlock spells aren't impressive but it's the invocations we're looking for there.
Where I think casters generally fall short at low levels is the DC 13 save against their very limited spell slots.
Warlocks get origin feats as an invocation option.
Good cleric, druid, wizard spells that upcast are an option. Command, Chromatic Orb. Tashas is a warlock spell.