For a small motor, I would usually say 2 stroke. Especially if you are getting a 9.9 for lake maximums, and not the boat max.
2 strokes are definitely lighter, unless you get into the new DI motors, but that is a whole new animal, and I won't go there for this post. 2 strokes often have a bit better torque. Think about it, you are firing every 2 turns, and not four. This is not to be confused with the common misconception that 2 strokes are stronger, as 9.9 horses is 9.9 horses, no matter how you skin the cat - the 2 stroke will have a bit better get up and go.
The noise is all dependent. Two stroke outboards are not all that noisy. Most of them are exhausted underwater, which quiets them out a bit. Sure, a 4 stroke outboard, made by Merc or Honda or somebody is going to be quieter, but those Briggs and Stratton motors definitely would not. I so far have not found a compelling reason to own that, unless you need to get in water too shallow for the water intake, as they are air cooled.
Mixing oil isn't much of a pain at all. Sure beats changing oil, filters, timing belts etc. in the four stroker.
For me, 2 stroke is hands down. The only 4 stroke I would consider would be a Honda, and that is because they are just great motors, and unfortunately don't make a two stroke.