Arbalest with loomed bolts should be able to do 90p or so at point blank range, being a guaranteed. You should be able to sometimes oneshot 40 armor people (not sure about hitboxes now) depending on if they have IF and how lucky you are with dice rolls (52 to 70 raw damage). Air friction lessens this A LOT though so at range it doesn't work and speed bonuses affect it a lot too, so it can change it considerably too. Not to mention head shots.
Crossbows and Bows have the same damage mechanics after the raw damage has been calculated, so against 40 armor we assume arbalester can do 90p at point blank. Long bow is 34p loomed, Rus bow 31p. Bodkins give 3 additional pierce, or alternatively damage type can be cut with tatars bringing it to +7 damage, but cut.
So we're looking at 41c or 37p before modifiers. Crossbows aren't affected by any player attributes, bows are. At a bow build of 21/21 or something similiar you can get your damage close, but you've also sacrificed mobility, melee capability and some accurace in your pursuit for damage. An average archer has absolutely no way of doing more damage than an arbalest on one shot - you need a very specialized build for it as opposed to arbalest users being able to have decent melee stats and good mobility.
Now, normal crossbow can do 66p fully loomed with fully loomed bolts. That's not that hard to surpass with a bow at all, but regardless compared to your investment of a couple of WM points the archer will need at minimum 5 points in power draw and additional points in weapon master due to power draw reducing wpf by 14 per point.
So, basically, if you are using normal crossbow, too bad, you aren't a proper crossbowman. If you're using an arbalest your burst damage is better. Speed bonuses, hitboxes and range play considerable roles in damage though, which can be a boon to archers. Super slow arbalest suffers a lot from a miss.
In terms of damage per seconds bows will win hands down obviously.
Play with
http://infinitum.dyndns.org/crpg/calc.htm to see what damage what does before speed bonuses, hitboxes, hold bonus and air friction.