The Phenom II x4 will have a l3 cache, the Athlon 64 x2 does not. As you wrote it, the Athlon is at 3.2, the Phenom is at 3.4 so the Phenom is faster. Also, as you wrote it, the Athlon is an x2, the Phenom is an x4, meaning 2 and 4 cores, so the x4 is ideally better.
In every way, the Phenom II x4 is better. Except in cost =P
Your question, while not...vague... isn't very helpful in your overall goal here.
If all you want to know which is better, then by all means the Phenom II x4, but if you are planning on upgrading or something like that, there are many other things worth looking over.