I used to use a Fiskars set that I think I got at AC Moore (orange plastic stencily-looking things) - HATED it!!! I had a hard time holding them still enough; they always slid around and I would end up with a little jagged piece on one part of the circle/oval. I don't remember the blade making a nice cut, either.
Now I use the creative memories set. LOVE it!!!! It makes a very smooth cut, and after getting it down with a few practice cuts on scrap paper, I don't think I have ever messed up when cutting a picture! It really works great!