There's a lot of talk about tone capacitors. People have theories and ideas about them. A lot of this information is not founded in reality, but rather in marketing and "mojo."

Your tone capacitor does almost nothing until you turn your tone control down. While potentiometers do allow for a tiny, minuscule bit of bleed-through, they are essentially an open gate or a closed gate when turned all the way in one direction.

Think of it like this:

Sound comes out of the pickup. It meets with the volume control. The volume is a gate that limits how much sound can get through. When it's turned all the way up, the gate is wide open. The guitar is loud. You hear everything that pickup has to offer.

The tone control is like a side gate. When it's turned all the way up, it is closed. Everything goes out the main gate - through the volume control. As you turn down the tone, it opens the side gate. It allows sound to hit the tone capacitor.

The tone capacitor only allows high frequencies (treble) to pass through. The treble that gets through is then sent to ground. It's gone. You don't hear this sound. What you hear is what didn't go to ground.

People have an idea that their tone cap will have a huge effect on the overall tone of the guitar with everything turned up. That is just not true. If you don't turn your tone controls down while playing, you can't really hear what your tone cap is doing. That's because it's just sitting there doing nearly nothing. Now, as mentioned above, there is a tiny bit of bleed through. We say the difference between having the tone control there and not is like turning your tone up from 10 to 11. It's really more like turning it up from 10 to 10.2 or something. It's almost undetectable. The bulk of your tone, with the exception of a tiny bit of high frequencies, is all getting through. You're not "hearing the cap."

In this graphic above, I tried to make it pretty simple to understand. This is a simplified diagram rather than a schematic that scares people off. Take note of the blue line - and how it passes straight through. See how the tone cap is down off the side? The tone you hear does not pass through that cap at any time. Even when the tone is turned down, what goes through that cap is gone. It's not heard.

Now as far as type of capacitors:

My advice is use a good quality cap. Don't spent $50 on super ultra special NOS oil in paper bumble bee etc... mumbo jumbo. Scientific studies using spectrum analyzers and oscilloscopes have shown that the differences in audio frequencies passed by capacitors inside a guitar is almost negligible. As long as the quality of the cap is decent, and the value of the cap is accurate, the sound will be nearly indistinguishable from brand to brand, type to type. There is a lot of marketing and mystery that goes into selling tone caps. There's also a lot of boutique brands just stamping their name on other products that are cheaper elsewhere. You pay the markup and still can't hear the difference.

The human mind seems to have more effect on what tone you perceive than anything. You just spent $100 on two caps for your Les Paul. You fire it up, and you're convinced it sounds better. Why wouldn't it? You spent a bunch of money. You should get something for your money.

Next time, spend $5 or $10 on Orange Drops or similar caps. Get the same sound at a fraction of the price. Go buy a bunch of beer with the money you saved.

Also good to note: Some people will go through cap after cap and then swap pickups, etc... without ever investigating whether the pots are doing their job properly. Sometimes you'll find a 500K rated volume pot that actually reads 200 or 300K. This will have a massive impact all the time at any volume. If your pots are excessively scratchy when you turn them, clean them. If cleaning doesn't work, replace them. The scratchy sound is corrosion or debris, or other failure of the pot inside. Since all of your tone passes through the volume pot, it needs to be working well... or you're definitely losing something.