Don't let the 5-8 speed thing throw you. It's referring to the number of gears on the back freewheel or cassette. If you don't ride your bike a hundred miles a week, then virtually any brand you find should be a "good" chain.
I'd go with a Bell chain from Walmart or Academy Sports. Many here will lambast me for that, but as I said if you aren't putting that many miles a week on the bike, why spend more. Although a really good brand isn't that expensive either.
Oh, make sure you size the chain to your old one. Replacement chains are typically too long and have to have a few links removed.