What is the best use for gold in Minecraft?
The "best use" for gold is fairly subjective, but there are a bunch of things that can only be made with gold:
Weighted Pressure Plate (Light) - Gives an analog redstone signal that is equal to the number of entities on it (max 15).
Powered Rail - Increases the speed of minecarts that go over it when it's powered with redstone
Clock - Shows the time of day
Golden Apple - Gives regeneration and absorption potion effects when eaten, 2.4 nourishment value
Golden Carrot - Used for making night vision potions, 2.4 nourishment value when eaten
Glistering Melon - Used for making instant health potions
Gold can also sometimes be traded with villagers for other items, and weapons/armor made of gold have a higher "enchantibility" (better chance of getting good enchantments) than any other material.
I use my gold for enchanted items that I don't use a lot like silk touch shovels for when I need grass blocks. Gold tools mine faster than any other tool and also have the highest chance of good enchantments.
Other than that If you use minecarts you might use most of your gold for powered rails. those take 6 golden ingots to craft but you get 6 of them every time you craft them.
You can also combine gold and melons to get potions of healing. which can be helpfull if you take a lot of damage. (I have dispensers all around my base which can heal me whenever I need to)
Having clocks around your base can help you if your base is underground
Other items that you are able to craft using gold are golden apples, these give you a nice buff but cost quite a lot. also the golden carrots that can be used for breeding rabbits, taming horses or making nightvision potions.
You can make Mojang banner with enchanted golden apple.
Like this
If you don't know how to make here is recipe
This is only for decorations this will not help you in singleplayer but if you play multyplayer much servers have shops where you can sell banners or trade to another player.
You can use gold for beacon too if you have much.