Its not quite that simple ... There are so many different cards on the market, and some may have more features than you need.
For example, do you want a single tuner card or a double tuner card? Do you want a digital card ... a card that supports hdtv? Does it have to be MCE compatible? Do you need a remote ... FM radio ... PCI, USB, PCI-E X1? I'm only scratching the surface ...
I like Hauppauge, although I don't think they offer a digital card. Simply put, they offer a good value for your money. They aren't the "best," but they fit the bill for most people very nicely. Win TV-PVR-150 series would be your budget card and the Win TV-PVR-500 would be higher end. There's also a couple "flavors" in the middle.
I think I would start by deciding what features you want and then go from there. You may decide a card by a different company better suites your needs. The "best" card for you will have the features you need at a price that fits into your budget.