My choices are as follows.
* Linux:
# Tilix - probably the best option in terms of performance, customization, looks and features.
https://gnunn1.github.io/tilix-web/
# Extraterm - in my experience the best electron-based terminal emulator in terms of performance. It has some neat features too. I catch myself using it more often than Tilix.
https://github.com/sedwards2009/extraterm
* Windows:
# CMDer - pretty much the only option. Has everything one needs, even built in bash on Windows. Useful on Windows 7 PCs at work that don't have WSL or admin rights to install more stuff.
https://github.com/cmderdev/cmder
* MacOS
# Plain old built in terminal is actually nice ;)
# Extraterm is alright too, but it's electron based and the old mac-mini does not really like it.
# iTerm 2 - never got around to fully configuring it, but everyone swears by it.
https://github.com/gnachman/iTerm2