The usefulness of an optic is in the eye of the beholder. The Simmons and NcStar are really two different types of scopes... here are my two cents (opinions will vary widely)

For making those 200+yd shots the Simmons 6-20x will be best suited. And if you go boating the Simmons will double as a boat anchor at a whopping 22 ounces + mounting hardware, and it's length would serve well as a tomato stake. That said, weight and profile probably isn't much of a factor for those who chose such a scope because most of their shooting is likely supported. Supported, high power optics are great for shooting at stationary targets from short to long distances. Unsupported at short distances or non stationary targets high power optics aren't too useful due to low field of view... you'll spend all day just trying to find the target. The Simmons has very clear and bright glass for $100 on sale. Probably one of the best deals out there for this type of scope/price.

3-9x scopes... there are a gazillion choices... but what the NcStar has going for it is tacticool compactness. It's style fits the rifle. Tacticool gagetry of an illuminated reticle and attached red dot are fun and useful too. Some folks have reported the height of the built in scope mount is too low to use comfortably. Some have had difficulty with the red dot hardware and sighting. The NcStar is also pretty hefty compared to just a simple 3-9x rimfire optic.

I use my 15-22 to shoot short distances at stuff that moves around... soda cans, rocks, twigs... whatever. A small and light red dot works well for that.