Depends on what you are looking for. The D3200 has more mega pixels, 24 vs 16 but the D5100 has better ISO performance. D5100 has continuous video focusing but the D3200 has a better external mic. The D3200 is smaller and lighter. The D5100 has built in HDR. The D5100 should be a bit cheaper too. For me, the only thing that would make me unsure is the mega pixel or ISO decision. All the other stuff I could care less about.
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