Well, there are certainly a lot of spells that could be improved in this way, though I probably don't agree with many of the suggestions here returning to the LFQW paradigm. To start with:
True strike - just needs to be Guidance for attacks.
Friends - Needs to be more usable but not overpowered for a cantrip.
Witch Bolt - probably needs to grapple the target.
Detect Evil and Good - need an 'At Higher Levels' clause that expands the range
Illusory Script - probably needs a duration until dispelled.
Goodberry - should probably consume components
Jump - duration should be upped to 10 min and a clause should be added that the extra jump distance provided by the spell does not count towards your movement allotment.
Protection From Evil & Good - Needs to expand the types it protects from. I get that it should not work on the 'evil' town guard, but having it not be effective against the Ancient Wyrm seems weird. Maybe it is effective against everything except humanoid, beast and plant.
Ray of Sickness - should not require a saving throw and an attack roll. Just an attack roll, no saving throw. Resistance to poison and immunity to the poisoned condition would of course apply.
Tenser's floating disk - duration increased to 4 hours. It is a utility spell, no harm in having it last a half day.
Unseen Servant - same.
Barkskin - loose concentration.
Crown of Madness - needs a rewrite so they attack the closest person they can reach, maybe loose concentration.
Find Traps - needs a duration of 10 minutes, maybe at the cost of concentration.
Ray of Enfeeblement - Affects Strength attacks, Strenth ability checks and Strength saving throws.
Bestow Curse - Range 30' (Only spell that is touch yet requires no touch attack), options need to be disadvantage on all attacks (not just against you), extra damage from all attacks (not just from you), etc.
Flame Arrows - loose concentration.
Feign Death - duration needs to be up to 8 hours.
Phantom Steed - duration needs to be up to 8 hours.
Vampiric Touch - loose concentration, needs to be an instantaneous touch attack that deals, say 7d6 damage and you get half in healing (can be delivered via familiar).
Blight - target that fails save falls prone and cannot get up or take reactions until the end of their next turn in addition to the current effects.
Grasping Vine - needs to restrain the target.
Phantasmal Killer - target takes damage before the save to end on each turn.
Stoneskin - loose concentration or the target gets advantage on Con saves as well.
Dispel Evil & Good - needs the full effects of Protection from E & G, plus needs to affect more creature types.
Eneveration - make it a bonus action to maintain every turn.
Immolation - make it target up to four creatures the caster can see in range.
Negative Energy Flood - make it a line effect that can hit more than one creature.
Flesh to Stone - remove concentration. The fail x before succeeding on y mechanic is sufficient.
Investiture Of spells - need to be bonus action to do the special attacks the spells grant.
Tenser's Transformation - loose concentration, add caveat that subject cannot maintain concentration on effects while spell is in operation.
Mordenkanin's Sword - so much needs to be done here.
Prismatic Spray - damage needs to be upped. It's really only good if a target gets hit by multiple rays.
Regeneration - duration needs to be 8 hours, can also be ended early to get the effects of a Greater Restoration.
Ali-Dalzim’s Horrid Wilting - targets that fail save have disadvantage on attacks and ability checks for one minute in addition to damage. Save every round to end effect.
Demiplane - so much, not sure how though.
Power Word ... - for Kill, targets above threshold get 100 physic damage. Other Words just offer an initial save to targets above the threshold.
Timestop - casting time changed to reaction
Weird - same as Phantasmal Killer. Still weak for 9th level spell.