Tell me your favourite rescue USB image and why!

Also rescue tips and tricks as that’s always interesting.

I have been using a Debian installer USB as I had it to hand (DVD image IIRC) but if I boot into a shell without mounting another root FS the number of utilities is quite limited (just busybox basics). For example just now I wanted gzip but it only had gunzip…

I feel like a shell started from the installer USB should have access to a lot more utilities because the files are there on the disk!

Does anyone know a way to set up a kind of USB like the debian installer where you can install packages from the installer into the live environment?