PC850 is the current name for PC48 and the cheapest 8-speed chain from Sram with chrome-hardened pins, which is a good as it gets for durability (870 and 890 are merely more shiny-looking). But KMC chains seem to be more widely stocked these days, also come with an easy joining link, and their model X8.93 is equivalent.
For the benefit of other readers: 8-speed chains are also good for 7-, 6- and 5-speed. And all Sram 9- and 10-speed chains are chrome hardened, so there’s no material benefit in trading up from PC951 and 1031 respectively.
This was first published in the August / September 2012 edition of CTC's Cycle magazine.