Download the trials, one at a time, and see how they work. I'm still more inclined towards Fluid Mask but once you have a serious play with them you find their shortcomings and peculiarities. onOne seems no worse than Fluid Mask so far as results go but the need to save as a PSD file then open it in PS was a bit of a drag. There are peculiar things happen using any of them, I still haven't tried Topaz, but you're never sure whether it's the plug-in or something else.
I think in the end you aren't going to get a programme that does a perfect job, it's probably impossible and Photoshop will get the best results, but we're after something that speeds up the process. Give them all a try, one at a time I'd say, and post your findings, it would be a real service. I'll do the same when I've slogged my way through the three of them. In the meantime if anybody out there has used or is enthusiastic about any of the masking plug-ins why not send a message?