"Although":

Hate it, to a degree irrationally disproportionate to its (slight) inferiority to "though." I know reasonable minds may differ, but there it is. "'Though,' not 'although'; 'on,' not 'upon'"; that's my motto (though one that may admit of occasional exceptions as to "upon"). Say, maybe that's what I should put on the T-shirts! Then again, maybe not.