Please help me choose a CPL !

I am looking for a CPL for my Tamron 15-55/2.8.

Since I've already overspent my budget this year, I want to go with Hvstar that seems to have good reviews and slow shipping .

I found these two offerings that are pretty affordable, is there a reason why I shouldn't get them instead of much more expensive B+W ? (I read about not putting a POS glass in front of good glass, but are these POS ?)

Are there any other ones I missed ?

Kenko
http://hvstar.net …ction=VIEWPROD&​ProdID=109

Hoya
http://hvstar.net …ction=VIEWPROD&​ProdID=657

(has a bunch of things I don't need along with the filter)

Any suggestions greatly appreciated !

Kenko and Hoya are two faces of the same company; either one of those should be OK.

Thanks.

The Kenko says "specifically optimized for digital applications", does it make sense or is it just marketing nonsense ?

The Hoya has front thread (Kenko doesn't seem to have one). Is it for stacking up other filters ? How useful would that be, I think adding one filter on top of another could degrade picture quality & reduce amount of light so it's probably not a good idea ?
I am leaning towards Hoya, there's just $5 difference, but they seem to throw in more than $5 of additional "fluff" so perhaps Kenko is a better choice ?

OK, nevermind, apparently I need front threads to put lens cap on.

Thank you for help !