This is a great point but just to add, if its a brand product you can get common issues that don't crop up for 6 months (e.g. xbox 360's red ring of death). So buy new but not on 1st day release, and do a quick research on issues people often have.
Same here, I was curious so looked it up. Apparently it’s still got plenty of bugs and a lot of debate going on on how many hackers there are, some say a lot. General stance is it’s better on unofficial servers.