Like KTMfan said, it's not as simple as purely two stroke versus four stroke. Some two-stroke motorcycles have a lot of flywheel weight and extremely smooth power delivery which is superb in the woods. Some of the KTM models, Husqvarna's and Gas-Gas's quickly come to mind. I have a 300 KTM that is an absolute tractor, it thinks it's a four-stroke. I use the clutch less on it than I have on many past four-strokes.
By the same token, not all four-strokes are super smooth and user-friendly either. Last year, I rode a YZ400 Yamaha and while I adored that motorcycle and had a lot of fun on it, it was not a good woods bike. The power was very abrupt and quick-revving, very two-stroke like, and it was prone to stalling on the trail. If you weren't on the gas at all times, it had a tendency to cough and die in technical situations. Some of the newer, high-tech thumpers do not have the flywheel weight and user-friendliness that four-strokes are known for. In my opinion, it's not just a four-stroke and two-stroke comparison, it's a case-by-case, motorcycle-by-motorcycle discussion. But in general, four-strokes are a bit smoother and easier to manage in the woods, although invariably you will have more weight to herd around.