My favorite ripper is the Rip Tweezer Combo found here
http://riptweezer.com/ I didn't know how much I needed the tweezers (already had several pairs) until I started paper piecing. It is wonderful having both items in one tool. The ripper point is very sharp and small. It had to be for me to rip 1.6 stitches on my paper piecing.
Second favorite is the "cheap" one sold at Hobby Lobby for about 2 dollars. I believe these are the same ones that came in my Brother sewing machine and stays sharp forever.