I've had good luck with Lexar and Sandisk, but I'd echo Necktie and treat them like tape stock. I try to keep track of how old my cards are, and when they eventually start getting me errors, I'll use that as a rule of thumb. Honestly, if you can get a year and a half of daily shooting out of your cards, I'd call that a win and plan to replace them every year or so. And if you can rotate them out so you're buying a few cards every 6 months, it shouldn't make a big dent.
When I was a chief, we used PNY cards in NX-5Us, and between the little write protect switch breaking off, and reporters losing cards, I don't think many even made it to a year and a half. I ended up slapping clear fingernail polish on the write protect switches before assigning them, since nobody shot enough to fill 2 cards in a day, and once that tiny piece of plastic snaps off, your camera will refuse to shoot anything.