I have two seam rippers that I love. The white handle clover and then my fav is a battery operated- The Quick Ripper. Talk about fast...turn on the Quick Ripper and a seam is undone in no time!!

I go through them pretty fast too. I once bought a pretty wooden hand carved seam ripper that allows me to change the ripper portion when it gets dull. Those little ones with the blue handle fit into the end perfectly.
It was gifted to my friend because of the drool she kept leaving on it...... :)