Usually whatever fits in best with the DE I'm using. I'm on Pop!, so that's Gnome Terminal currently. I'm excited to see when System76's Pop!_OS's COSMIC Desktop will bring with an alacritty-based terminal emulator.
I'm going to be honest, as long as the terminal does its job reasonably well and with good readability then I'm pretty much satisfied. It's one of those tools that I want to just work well the first time. I've become a man of simple tastes in my (not so) old age.