Link (Rider) will give you a random amount of mushrooms, a weapon or perhaps an item for your horse.
Zelda will reward you a random selection of plants or even a shield!
Link (Archer) will give you a random amount of meat and fish, and you may also receive a useful bow or arrow!
Guardian will reward you with metal boxes containing useful items or maybe even "ancient parts".
Bokoblin will give you a variety of meat and maybe his favourite weapon.
The Champions amiibo will reward you with materials, weapons and special headgear inspired by their Divine Beasts.
The Wind Waker
Zelda will reward you with a random selection of plants.
Unlocks Wolf Link, who will attack enemies on his own and help you find hidden items.