I'd pick the i5 any day.
Don't be fooled by the AMD's eight cores; they're actually pretty weak on an individual basis and very little software will utilise them all. The AM3+ socket has been around for a long time and I wouldn't expect any more processors to be developed for it. AMD seem to be concentrating more on their APU line, which uses the FM2 socket.
Don't get me wrong, I'm not a fanboy, but AMD haven't released anything new for nearly a year and they simply can't match Intel for raw performance. They can compete at the lower end of the processor scale, but once you get into i5 territory, there's little reason to consider AMD quite honestly.