Do you already own recording software?
I've only used the 002 (I have the table top unit, but the pres are the same) and I can say that they are indeed excellent pres and convertors. There are better, of course, but they are great for the price.
If you are seriously concidering digi products, the Focusrite pres on the Mbox are fantastic, as well. And its a lot cheaper than any of the other option you've listed.
If your main goal it to get great pres for vocals only, concider getting a basic audio interface with a S/PDIF input and sinking your money into a dedicated preamp with digital outs.
Good luck!
Chris