Few things to think of if your leaning towards a bike. Im seeing this more and more where bikes are being banned off trails due to noise. Also out of all the trails i ride very few you would ever get a bike up with out lots of work if you even make it at all. Unless your a very easy rider usually bikes will spin on throttle and going around corners damaging trails. Not saying atvs don't do some of the above but much easier to control. Iv seen far to many people buy bikes because all their friends have one, its faster, etc and they sit in their shop 90% of the time because it was to much work getting through the trails.
If you are able to borrow/rent both a bike and atv at some point, go find a fairly good trail and take them both up.
If you are able to borrow/rent both a bike and atv at some point, go find a fairly good trail and take them both up.