I bought one at Wal-Mart for less than $1 years ago, and I love it. Or course, you can't get them there any more.
Then, I heard about the Fons and Porter ones. They are very comfortable to use, but being round, they have rolled off my sewing table and the blade breaks off when it hits the floor. I've been through 2 and have decided not to buy a round one again.
I bought a Singer with a gel handle at Jo-Ann's yesterday. We'll give it a whirl.
However, one of my students had a really neat one. I can't remember who made it, but it had a seam ripper on one end and a tweezers on the other. Very handy!