zsh + zinit  + powerlevel10k  > fish + starship. Powerlevel10k and zinit make prompt initialization time with all my plugins much lower than the equivalent setup in fish; I can start typing as soon as I open a terminal without breaking up my prompt.
gotop/ytop complement glances/htop. They offer a really sleek TUI that uses braille characters to draw graphs.
Poetry > Virtualenv for working in venvs in Python projects.
Distro packages > pyenv, rbenv, nodeenv. Most distros provide packages for multiple interpreter versions, and only use one by default. For example, Fedora uses symlinks: /bin/python -> /bin/python3 -> /bin/python3.8; I also have python3.9 beta, python3.7, and python3.6 installed for testing.
delta  > diff-so-fancy and colordiff. Delta combines language-specific syntax highlighting (foreground) with diff highlighting (background).
nnn  > ncdu. It has the functionality of ncdu when sorting by disk usage on top of being the best file manager I've ever used.
It's the best file manager I've used. It gives you 2 default panes in the terminal, and you can use vi-like commands to operate on one or multiple files. Especially good for operating on multiple files - for example, if you want to rename multiple files, you select the files, and edit the filenames in vi.