I've used xterm, rxvt, kitty, and now alacritty. I like alacritty because it's fast and simple. The only thing I don't like is that the default color scheme is off. If you run tmux in something like xterm, the bar is green. But in the default alacritty, it looks more yellow.
So I have this in my ~/.config/alacritty/alacritty.yml:
# XTerm's default colors
colors:
# Default colors
primary:
background: '#000000'
foreground: '#d8d8d8'
# Normal colors
normal:
black: '#000000'
red: '#cd0000'
green: '#00cd00'
yellow: '#cdcd00'
blue: '#0000ee'
magenta: '#cd00cd'
cyan: '#00cdcd'
white: '#e5e5e5'
# Bright colors
bright:
black: '#7f7f7f'
red: '#ff0000'
green: '#00ff00'
yellow: '#ffff00'
blue: '#5c5cff'
magenta: '#ff00ff'
cyan: '#00ffff'
white: '#ffffff'