Have a look at OS-2 Overdrive-Distortion by Boss as well.
A good site to get reviews on products is http://www.ultimate-guitar.com/reviews/
http://www.ultimate-guitar.com/reviews/.
I think you should look into as many products as possible go to a shop and play with them. Forget this and that artist says they are good as they are being paid to say it. Get what you feel sounds better to you. Also look at how hardy the thing is. This is more dependant on your playing style.
My personal view on boss is they are simple but built like small bunkers. So they will no brake in a gig. However they use a 9v battery and you should replace this before going on a gig they loss alot of the pitch and effect on a low battery.
I'll add something later on.