I have both and used both.

I really, really like my dremel. I ordered a small purple one off of petedge and it's great. First I ususally trim the nails, then use the dremel. It's my favorite for Jack (and Shadow) because of the black nails. You can also round them off nicely and they look better.

Because I'm the only one to do their nails and since I can't do them regularly the dremel is really nice because you can get them a lot shorter with it.