i like the, THE storm knee shins combo. super nice looking. pretty expensive though. if your looking for a cheap one, just look at the 661 race, or lower. good products, good price..
picture of the THE pads.
Unsecure image, only https images allowed: http://www.bmxultra.com/news/2006/the/the_knee_shin_guard.jpg
people are going to tell you alot of different things but it all really comes down to personal preference. if you can try out a few different ones. as far as myself... i like the race face pads, but at the same time i know i've only tried a couple different pads out. I'm sure that the TLD and THE pads are excelent but i don't really know cause no one sells those close to where i live so it would be a bigger drive than what its worth just to get some shin pads.