One of the GNU Emacs packages that I use is which-key (which is now in GNU Emacs v30). I use it because I don't always remember specific extended key bindings (ones that start with a prefix) that are available to me, especially in MH-E , which effectively has its own set of key bindings for a large collection of commands. Which-key gives me a useful but minimal popup prompt about what's available and I can usually use that to navigate to what I want. Recently I read Omar Antolín's The case against which-key: a polemic , which didn't convince me but did teach me two useful tricks in one.
The first thing I learned from it, which I could have already known if I was paying attention, was the Ctrl-h keybinding that's available in extended key bindings to get some additional help. In stock GNU Emacs this Ctrl-h information is what I consider only somewhat helpful, and with which-key turned on it's basically not helpful at all from what I can see (which may partly explain why I didn't pay it any attention before).
The second thing is a way to make this Ctrl-h key binding useful in combination with which-key, using embark and in fact I believe a number of my other minibuffer completion things. That is to bind Ctrl-h to an Embark function designed for this:
(setq prefix-help-command #'embark-prefix-help-command)
As illustrated in the article , using Ctrl-h with this binding effectively switches your multi-key entry over to minibuffer completion, complete with all of the completion add-ons you have configured. If you've got things like Vertico, Marginalia, and Orderless configured, this is an excellent way to pick through the available bindings to figure out what you want; with my configuration I get the key itself, the ELisp function name, and the ELisp help summary (and then I can cursor down and up through the list).
The Embark version is too much information if I just need a little reminder of what's possible; that's what the basic which-key display is great for. But if the basic information isn't enough, the Embark binding for Ctrl-h is a great supplement, and it even reaches through multi-key sequences (which is something that which-key doesn't do, at least in my setup, and I have some of them in MH-E ).