Depends on how many crossbowmen you have against the number of bowmen.
If it's not something silly like 100 to 1, and something closer like 40 to 25, then I'd probably choose bowmen. If the difference is 100% or more, I'd think about it... But it also depends on a LOT of factors).
First of all, we must agree on what kind of crossbow/bow are being wielded. Are we talking something suitably medieval like regular wooden bows and crossbows? Or are we talking about modern light metal super-tuned bows and crossbows with laser sights (I actually know a person who owns a sports bow with laser sight -_-). Either way it would be unfair to compare something of medieval quality against something of 21st century quality.
So, uh, with that rant out of the way...
Ya'll have to consider that bows have many advantages over crossbows, but crossbows are easier to use. Some of the advantages of bows include improved mobility compared to crossbow, lighter or better distributed weight, potentially really fast attack speed - bows are the medieval equivalent of a machine gun if held in a well trained hand that can release an arrow a second or similar numbers compared to maybe 1 arrow every 3-4 seconds (or slower, if you consider the bigger kind of crossbows. So it's probably between 5 and 10 seconds), and so on.
Bows have about the same range as crossbows, bows are lighter than crossbows, bows can potentially be shot on the move, although I imagine it would make them way less effective, bows can be rearmed almost instantly even on the run - and crossbows would require much longer, even in the smaller models where one doesn't need to use levers...
Woah rant.
And crossbows are cooler.