Don't go for AM3 or AM3+ its a dead socket, no upgrading it in the future.
Everybody says that every 2 years whether it be about a Intel or AMD cpu. The current 8320 is probably as old as the 3570k, which is a dead socket too. And the current, working on 2 years old Intel one, will be dead in a year or so too.....point is. buy for performance now..if you plan to upgrade in 3-5 years it doesn't matter which platform you are on, you'll have to upgrade CPU/mobo anyways...plus DDR4 is coming soon.