Depends on your uses for the machine. AM3+ opens up the potential for superior performance, across the board. Of course, if maximizing performance is your goal, you should look at an Intel system unless your budget is severely constrained. If you want to absolutely minimize complexity, while still getting good general performance, then FM1 would be a decent choice.
If you are contemplating a new build, you will get the best and most relevant advice by starting a new build thread and filling out the sticky on how to ask for new build advice.