PCI or PCIe?
To say one is much better than another in my opinion is not correct, it's more of choosing a card that is either compatible with or supports the things you want to do with it. For example, do you need a card that can do wireless B/G/N? Or does the card need to support monitor mode? Maybe even a card that had 2 antennas one for a directional yagi and a omni directional? Or maybe you want to check on if the chipset supports packet injection... All things considered you can pick a good card, check out newegg.com and look at some of the reviews and that will give you a place to start. Then head over to http://www.aircrack-ng.org/doku.php?id=compatibility_drivers&DokuWiki=a87856f50282e13f10f5453658bc640d#compatibility and check for compatibility for mon0 and injection, because if your using bt5 im guessing you'll want those...
Good luck