Forget Mega Pixels at the moment. Straight away go to D7000. Body costs 44K these days (Brand New). + 50mm 1.8D which is around 11K or so. If u need wide angle lens, u will purchase it little later.
In your 50K range, add 3 or 4 K more, just buy D7000, u will not regret it. If u opt for d3200, d3300 or something else, later u will switch to amateur body, then d7000 again gonna be ur first preference.
I personally used both Nikon and canon.
I usually do Landscape photography. And Nikon is very very good in landscapes & Street Photography, though i used just a basic lens. The depth of detail in wide angle shots is far more richer than canon. But in long range zooms, sharpness is usually only around center of the frame.
For portraits & Sports Photography, canon is very good. reason is it gives very sharp result from each edge till center of the frame at 200mm range etc. As in both kind of photography, very tight framing is used to capture the moment.
Many fellows argue about expensive range of lenses in Nikon as compare to canon.
First of all, canon has more variety of lenses as compare to Nikon, but Nikon lenses are equipped with better optics.
Canon accepts many brands of lens, but not much in case of Nikon.
In case of 50mm Prime lens of both variants,
Canon 50mm is around 10K, and gives auto focus functionality on every EOS model of canon. Its very sharp and valuable lens one should have.
Nikon 50mm has 2 versions
50mm 1.8D --- Its is an excellent lens, not give auto focus functionality of D3xxx and D5xxx series. Its smallest aperture is f22. But on D7xxx, auto focus works very well. Noisy while focusing. Price 11K around.
50mm 1.8G --- Again its an excellent lens, auto focus works on every model. Smallest aperture is f16. Price 19K around.
But remember, lenses are not like cell phones, which one could replace after every two months or so. Buy once, but the good one.
Rest of the lenses of canon and Nikon are nearly in the same price tag. say if one can afford a 120K lens, then its not hard for him to buy 125K or 130K worth of lens of the same specifications of other brand. ( Its just an example).
Now come to mega pixel. Anything above 8 mega pixels is sufficient to take post card size prints.