This is small list of commands I find very useful. This list will never be final because I plan to update it regularly. Also I will not list standard GNU commands.
dog- a command-line DNS client which is not pain to deal with
downgrade- an useful tool for downgrading packages on arch based operating systems
neofetch- command you can run to remind you that your distro is just meme
nmap- network exploration tool and security/port scanner (if it is good enough for trinity it is good enough for me)
tldr- a simplified man page that shows most often usages in bullet points
yay- a pacman wrapper which helps you with AUR packages written in GO
cmus- basically a command-line version of iTunes
cointop- htop for crypto currencies
fzf- a command-line fuzzy finder
ncdu- a disk analyzer which will help you find large files and unused files for easy disk space maintenance.
neomutt- based email client
neovim- the only good text editor ever made
rmlint- file finder capable of generating list of duplicate files and user friendly shell scripts for their removal
sysz- terminal UI for systemctl with fuzzy search