Gnome Terminal because of its text smoothing (and because it adheres to a set of human interface guidelines).
I'd recommend mrxvt, a superset of rxvt. It's lighter, has support for tabs, fonts, transparency, etc.
https://bugs.launchpad.net/debian/+source/vte/+bug/29787/com...
rxvt and friends gave me problems using truetype fonts. They have their own code for calculating widths which gives the wrong answer even when it's monospaced.
I wish there were more terminals. It may seem like there's a lot but they are derived from a fairly small number of roots and they inherit all of the bizarre behaviour.