A lot of chains for lower speed bikes are now listed as 5-8sp, meaning they are an 8sp chain. So you should be fine with one. I also prefer KMC to SRAM, but 8 speed chains are typically pretty durable so you should be good with either. Just make sure you cut it to the right length and keep it lubed.

As you go up in level of chain they get a little lighter and often get better plating. I'm guessing the weight difference won't matter to you but you may want something with a better finish if you ride in the wet.