As far as my preferences, I think the PS/2 3V boards were my favorites. They were far more repairable than the PS/3 boards, and seemed to stand up to some abuse better as well. As far as LED's, I've equipped a ton of PS/2 stuff with LED's, a 220 ohm resistor and the LED and the job is done, easy-peasy. While the PS/3 boards introduced more outputs for fancier lighting, without the ability to access the firmware to customize the functions of the outputs, the allure of that feature is limited, at least to me.
That's not to say the PS/3 boards didn't have some cool features, I just think they sacrificed serviceability for those extra functions.
