At one point, back in the day, it was much more important which race you chose for monk, and it was Iksar which had the major advantage (like was said, AC bonus and higher HP regen), but nowadays I would just pick what you want to look like, cause your gonna be stuck with it and in the higher end game the class bonuses are negligible...that being said, Iksar's obviously look the best, by a long shot
Iksar Monk in the Scars of Velious Iksar Monk preparing to attack Iksar Monk displaying new 'nunchuk' weapon
I've been saying since they introduced the Luclin models that Iksar look like little Godzillas. Glad other people see it too.