Yup, I agree on that. Don't go too cheap on filters. I see some posting about having to purchase a better quality filter just b/c the first cheap one wasn't good and affecting IQ.
I bought a circular polarizing B+W filter, and am pretty happy with it. Solid, good performance, easy to clean, no problem with IQ and more.
There are other good brand filter out there. Hoya pro 1 and B+W filters (the MRC and kaesemann) seems to be very popular. some of the others are marumi, singh ray, nikon. there are more that some trust, but these are the more popular.
You have to be careful with buying Hoya's filters b/c Hoya's filters comes in a large range and some of the cheaper one aren't that great. But the higher price one are good like Hoya pro 1 and Hoya HD digital.