The A8 is much newer, uses much less power, has a half decent IGP and is on a newer socket, so if it was a choice between the two I would pick the APU over the Phenom 965. However, performance is fairly similar, with the Phenom 965 having the edge. In some scenarios, the difference is very small, in others it's quite pronounced.
That said, I find it quite difficult to recommend AMD CPUs for high-end gaming at the minute as the performance just isn't on par with the equivalent Intel CPUs.