Well that would depend on how much you are looking to spend and if you are planning to use a separate graphics card or not.
The APUs run on socket FM2 and have decent integrated graphics if you are on a limited budget.
The FX line uses socket AM3+ and have no integrated graphics so a dedicated card is required.
i Have a separate graphics card radeon HD 6670 , does the FX line include quad core ? e.g FX4100 ?