Favorite item: Zelink in Skyward Sword was adorable.

Least favorite item: Link/Saria or Link/Ilia.

Okay that was hilarious but now I'll actually answer. Assuming we're only talking about side-items and not equipment like Sword/Shield.

Favorite Item: Bow/Arrow. Kind of a standard response, but I just feel so naked without it. It lets you hit switches, fight distant enemies, and it's generally fun to use. It also usually has some awesome upgrades and extra arrows.

Least favorite item: Probably the Spinner in Twilight Princess. It was useful in one dungeon and seemed stupidly impractical for any other application. I remember trying to fight Bokoblins with it in Hyrule Field and just looking incredibly stupid.

:Fave: Tempered sword from Link to the past, love the sound it makes

Least fave: Bombs

Favorite: (I don't count sword or shield) ocarina
It brings SO MUCH to the table
:)
Least favorite: compass

They were useful in N64 games since that finally place your cursor triangle on the map hud screen and inventory screen. Thankfully they removed that limitation but weakened the compass to a treaure chest locator. But everytime I pick one up after the N64 games, it feels like the game is telling me "Hey, remember when you kept running around the walls figuring out where you are? Thankfully you dont need me to do that for you anymore, huh?"

My least favourites: deku nuts and book of mudora (for obvious reasons).
My favourites: nice fire rod from a link between worlds. That thing killed everything! fun item: roc's feather.

My favourite: Fierce Deity's Mask.

My least favourite: uhhh...

Favorite: Hoover Boots (I like to mess around with them)
Least Favorite: Lantern

Favorite: Magic Spells
Least: Fishing rod

Favourite: Hookshot/Longshot/Clawshot/Double Clawshots. Always super fun to use, and very versatile
Least favourite: Deku Nuts. Never, ever found a good use for them, except for maybe one or two times in Majora's when you're a Deku Scrub

Completely forgot about the Telescope, now it's definitely my least liked item. So useless... I used it about 1 time.