How to cash out of BTC: when the time comes?

I was hoping that some people in the know here could comment with the best methods to cash out of BTC. I am thinking it may be useful for people in the community.

First of all, I am personally not planning to cash out any time soon. I am keeping my BTC on a hardware wallet.

So if someone was going to cash out to USD with a large sum if money, let’s say 100k or more. Which exchange is the cheapest in fees but also a legitimate and trustworthy site?

If you know of a good source to use, based on experience please share! Or if you know of a service to avoid please share that as well.