A lot of common magic items rely on creativity and the willingness of DMs to play along. If you don't have a flexibly DM, your mileage may vary drastically.

The Literal Good Items

Moon-Touched Sword: This helps deal with Darkvision issues if you're a race that doesn't have it; people tend to overvalue Darkvision, so I'm not incredibly high on the Moon-Touched Sword but in a category that doesn't have many direct/literal power increases, this is one of the better ones.

Imbued Wood Focus: Gives a +1 bonus to damage rolls on a particular damage type. There's some question on how useful it can be with all DMs because focuses are complicated and it's unclear if you're able to cast spells that don't require Material (M) components through a focus (even if your other hand is free) but I'd encourage all DMs to simplify the complexity here and give the bonus on all damage rolls of the element type as long as the player is holding the focus.

Clockwork Amulet: You can skip rolling a d20 on an attack and guarantee a 10 instead once every day (refreshes at dawn). This ability replaces the roll, so you can use it in situations where you have Disadvantage and you can use the 10 instead.

Everbright Lantern: This sheds a lot of light.

Orb of Shielding: It's a focus and provides some damage prevention at the cost of a Reaction (but not a spell slot!).

Ruby of the War Mage: Turns a melee weapon into a spell focus, it doesn't allow you to perform the Somatic components of a spell so it's a little awkward (and most classes that want access to a Spellfocus while holding a weapon or shield already have something like this available to them).

Dark Shard Amulet/Hat of Wizardry: This allows a warlock (or a wizard) to wear their spellfocus, potentially freeing up the caster's hand for a shield or weapon instead.

Consumables

Feather Tokens:

Situational

Coin of Delving: Sheds dim light, so it could be used to mark the distance of something in the dark -- otherwise, determining the distance of a fall could be useful if the party doesn't have access to spells or traits that can reduce fall damage.

Horn of Silent Alarm: Being able to warn a person within 600 feet of you without alerting other people has some potential uses, especially for the scout of the party.

Instrument of Scribing: Potentially useful (maybe saving a spellslot or cantrip space for bards), requires a bit of creativity with 6-13 words but might be nice if pen/paper wouldn't do the trick.

Mystery Key: If your party isn't proficient in Thieves' Tools and doesn't have Knock, this has the potential of opening a lock (or maybe guaranteed to open a lock, given enough time and a DM willing to let you retry).

Wand Sheath: If you have a wand, this is handy (no pun intended).

DM-Dependent

Boots of False Tracks: It's limited to humanoids but it should complicate things if the party is being tracked by someone/something or a lone player is trying to sneak around.

Bottle of Boundless Coffee/Tankard of Plenty: This one is incredibly DM-dependent, but I can see situations where offering coffee/ale in a social situation could grant advantage on a CHA check or it could prevent an NPC from freezing to death.

Charlatan's Dice: Play some dice games at a tavern during your downtime. A creative/willing DM might even allow you to roll the Charlatan's Dice at the table for certain in game checks -- DM asks for an even or odd roll, roll that d6 and you get to choose on a 6.

Note: There's some room here for homebrewing if your DM is willing to break the 4th wall and allow you to roll a d8, controlling the result on an 8, with spells like Chaos Bolt.

Instrument of Illusions: This seems like something a willing DM would give advantage on Charisma (Performance) checks when using this item.

Staff of Birdcalls/Staff of Flowers: Both have minor effects that can probably be covered by cantrips (especially Birdcalls) but Staff of Flowers doesn't require Druidcraft.

Note: All staffs and wands should be considered spellfocuses for classes that can use them as a spellfocus, even though this description doesn't specify it's a focus the rules assume they are.

Dependent on RAW/RAI

Hat of Vermin: See the Bag of Rats problem/exploit.

Rope of Mending: Worst case, this is 50 feet of rope and that's useful on it's own. This might work with spells like Snare that consume the rope, it's a fairly reasonable ask to see if you could recover the rope after the spell is triggered or dispelled.

Talking Doll: With some creativity, you might be able to stretch the usefulness of this doll to do things you might not otherwise be able to do. Extending the example provided by this item, you could see if an evil-aligned person picked up the doll, it could say "Don't hurt me!"

Fun Items

Ear Horn of Hearing: This is the type of magic item that will make a DM groan when they think they "got" the party.

Heward’s Handy Spice Pouch: I don't think garlic is considered magical. Even without that, finding out if someone loves (or hates) a particular spice could do some fun things in social situations -- and hey, you could always sabotage a meal with 10 servings of salt (or sugar). As for cilantro specifically, 4-14% of the population thinks it tastes like soap so I'd hope three'd at least be a d100 roll to see if that works out.

Tankard of Sobriety: It may require a Sleight of Hand or Deception check, but you should win every drinking contest for the rest of a campaign with this item.