I am kinda partial to Crucial myself.
There are many good brands.....here is "general tip" to keep in mind. (anyway, this is what I look for)
Look for memory that has lower timings, and lower voltage. Higher voltage is a way to get memory that may not be quite as "perfect" to run at faster clocks. So if you find a kit that has lower timings AND lower or standard voltage, you can pretty much be assured the memory modules tested well, and are quality parts.
Corsair is one that always puzzled the crap out of me. Their parts need some of the highest voltages of any memory on the market compared to their latencies, they are amoung the most expensive, but a lot of people seem to really like them, and I see a lot of test sites promoting them. Maybe not as much lately, are people starting to catch on? It just does not make a lot of sense to me!