Both modern compound bows and crossbows are capable of lethally killing an animal out to 60-70 yards maybe even further, but you have to understand that what everyone here is saying. Your goal should be to shoot the animal lethally within your range, not the weapons range, for that, you can choose either one. The ability to shoot for most individuals beyond 30 yards accurately and consistently falls into the category of skill and experience which both need to be developed over time. You cannot just zero in a bow sight or crossbow scope and expect that to be it.