Advise on buying Nikon d3200 or d5100

At these prices, I'd say D5100. Out of the big three (Amazon, Adorama, B&H), the cheapest for both is $596 new, while you can get a D5100 for only $449 refurb and D3200 for $514 refurb. I'd recommend doing what I did, and getting a refurbished D5100. Mine came with only 3 existing actuations and looked almost new.

If you're considering refurbished, then the D5100 is unreservedly better. If you have to buy new, the decision's a bit tougher since they're now the same price. At this point, you have to consider whether you really need 24 MP. Often it just takes up space on your drive, and only offers a 22% increase in linear resolution. Also consider the quality of the kit lens, which may not be sufficient to resolve 24 MP. I've been seeing its sharpness limitations on my 16 MP D5100 already, so 24 MP will probably just be overkill.