It depends whether or not you have a quality AM3+ motherboard to begin with.
If you have a Gigabyte GA970A-UD3P, MSI 970 Gaming, Asus M5A97 (non LE), or any 990 boards, then upgrade to a Fx 8xxx if its a good price. However, if you don't have any of the boards mentioned, then your mobo can't handle an upgrade and best to build new system.
To buy a new Intel + mobo + OS would pricier.
P.S. - The 1150 is also dead. No new CPU is being released for that socket. If going for the Intel route, then go with 1151.