I have used the magnetic lasso occasionally. I find though that if you make one mistake with the magnetic lasso, it can be very hard to correct. I've been using the Pen Tool for a while. zaipixie did a really good header tutorial using the pen tool Here
I use both Paint Shop Pro and Photoshop. I use Paint shop pro to clean up and smooth out some screen caps. QAF cans can be very hard to work with at times. I find that Paint Shop does a good job cleaning them up. This tutorial was all don in Photoshop.