Kind of depends on what you're up against and what your play style is. The crossbows extra range is a major boon in terms of flexibility and even armies that are generally heavily armored usually have some lightly armored or small support units that are the perfect target for crossbows. There's also no difference between a crossbow and a handgun when shooting at many monsters, such as giants and helpits. I would consider crossbows to be better most of the time.
If you've got a thing for sniping with hochland long rifles and you play a more stand-offish style and you usually face high AS armies, then the more specialized handgunners could be for you. Whereas the crossbows will get you an extra turn of shooting if you go first, you can get essentially the same advantage with handguns by backing your line up by your opponent's M. You won't get to shoot in turn 1, but you will in turns 2, 3 and probably in turn 4 as well because the charge range for your opponent in turn 4 will be extremely long. You might even get a bonus round if he fail-charges your handgunners at the long charge range. Of course, if you use crossbows with the exact same tactics described above, it's quite possible to get 4 turns of shooting, instead of just 3.
But still, generally go with crossbows, the range really makes the difference.