What is the benefit of ores obtained from silk touch?

Antoine Hejlík's answer covers most of the benefits, but there's a few extra ones;

- There's several blocks that can mainly only be obtained through Silk Touch

Ores, mycelium & grass for spreading purposes, and Ice Blocks

The other answers (and comments) seem to be forgetting about the dear Ice Blocks, even though they have several uses!

• Can be used to create a variety of traps
• Can be used to to amplify the Soul Sand slow (Place an Ice Block directly beneath Soul Sand)
• Can be melted on demand to create water (and moved around beforehand) replacing a piston/water setup, and giving 'some' freedom.
• Can create 'speed' tunnels. Running and jumping on ice in a 2block tall tunnel is faster than running!

All thanks to silk touch :)

I haven't played Minecraft in a while, so there may be other uses now!

the main use of silk touch is for mining solid stone as opposed to cobblestone.

Silk touch mines the initial object in place of the item it drops (cant remember all the objects it affects though)

But say you were building a stonebrick castle, a silk touch pickaxe would mean you would not need to refine the cobblestone, as silk touch picks would directly mine smoothstone for you.

this means you can create the stonebricks faster and without using as much coal.

Theres probably more to it that ive missed but thats the key point, use your silk touch to mine objects that would normally drop other items, to get the original object. (Perhaps glowstone for example - give that a try and you may get a solid block in place of dust, but dont quote me on that one as ive not done this in a looong time.)

EDIT/tl;dr - When using silk touch for mining, its typically used either for transporting blocks like grass that arent otherwise easy to access, to obtain blocks like glowstone or stone brick more resource efficiently or to mine ores directly for decorating purposes. Another possible use would be, as mentioned by @Robotnik below, would be to try and move ores to locations that are easier or safer to mine with other pickaxes with other enchantments. Taking a redstone ore block up uses less inventory space than 5 - 10 redstone dust, meaning you can move it up more efficiently to mine again later with a higher droprate pick, or just to save inventory space when mining.

In addition to Antoine Hejlík answer if you plan to have your world alive in upcoming patches and provably store those resources its always better to save raw materials for example if they add the fortune IV enchantment, in the other hand if fortune is nerf you can process before updating.

Redstone ore blocks light-up when you touch them. Since this counts as a block state change, it will trigger BUD Switches (redstone circuits that create a signal in response to a block changing). This is useful when you want to make a contraption that doesn't use any visible levers, buttons, or plates, such as for a booby trap or secret door.

Positioning redstone ore blocks can be done one of two ways

1. Pushing them with pistons
2. Using Silk Touch

The latter is a lot less tedious

It doesn't affect just ores. Having a silk touch can help you mine certain objects without breaking them. For example, if you mine glass or glass pane with a regular pick, it destroys it with nothing left, or if you mine glowstone using a regular pick, it will give you 2 or 3 glowstone dust, which is 1/2 or 3/4 of its regular value.

Plus, with the ore block you can also make traps to keep trollolololols out of your territory by using them to set traps or something, because it also makes mining stone give you just stone instead of cobblestone.