I have the ginghers with the retractable blade. I love it. I got it at Joann' s with 50% and another 20% off. off It is sharp sharp. It does have extra blades, too. I have about 5 others, but this is my go to ripper.

I have a couple that I like: one is the Fons & Porter Ergonomic one, the handmade wooden one, and also the one on the scissors that I have for my LA.

HAVEL surgical blade ripper.....it is the greatest.

It is easier to use scissors to take apart clothes, just CUT the seams off, you do not loose much usable fabric and it is a whole lot quicker. If I was to rip out the seams I don't think I would get any sewing done :) Bonnie Hunter has a great video on deboning a shirt. I have watched it a lot.
http://www.youtube.com/watch?v=zS-09AYE0fM

I have used a lot of different brands including clover, granger and the little blue one all work pretty good, but most of the time I just use xacto knife I run the very point on a piece of sand paper to dull the real sharp point. dose a great job cheap to replace blade. Ball point pen cover will act as a cover

I'm like KalamaQuilts mine is from the sixties or maybe even earlier as it was my grandmother's. It's got a white handles and plain as can be but it sure does work! lol

I use my 45mm rotary cutter that I use to cut fabric. It is always on my sewing table and is always sharp. Takes a little practice, but I think it is the " Best".

The best one is the one that is both comfortable and works well for you.

It's the Gingher seam ripper. I have one, and I LOVE LOVE LOVE it! Won't use anything else. You can get replacement blades which they say is not needed because the curved blade doesn't get dull. However, after taking apart countless blue jeans for quilts for my nieces and nephews, I did change the blade. So if you get a chance to buy one with an extra blade, do that. It's worth it.

One of the nicest things about this seam ripper is that the very, very sharp curved blade retracts completely into the handle, so it's safe to leave in plain sight in your sewing room.

I also had an old seam ripper from my high school Home Ec (1975-79) however, I just bought a new one and WOW ~ could not believe the difference. I never realized how dull my aqua handled ripper had become...