I am going to do my best to answer this question in terms of reality. Basically, it doesn't matter how many megapixels your camera has! Too many of us are falling for the hype put out by camera companies wanting to sell newer, "better," bigger....and stress that "bigger is better." This may be true in some areas, but not in cameras.
Let's go back a bit to film....when we all used film, we knew that the film was all the same that we put into a camera.... Kodachrome, PanX, Ectachrome, Kodacolor, Agfa, etc....all the same film, with the ability to give all the same results...BUT ability and results were two very differnet things. The best of film ...the very best available to all of us...was the equivalent of 6 Megapixels !!!!!! BUT, using the same film in different cameras gave very different results! Why? Because of the camera (actually)... the LENS and how the shutters, light sensors, etc. worked. In those days, the ideal 35mm was considered the Nikon due to superior lens crafting and mechanics. Larger format film would give better results for enlargements (2X2" film would give better large prints because the pics had to be enlarged less for the same size print. 4X5" format was considered the Portrait camera .... no matter what the enlargement, grain would not be seen IF you were looking for grain. AND the 4X5" camera was used for news services, for its negative size was easy and fast to handle for news services. BUT, no matter how you looked at it, the FILM was the SAME....
Now we have digital, with up to 20+ megapixel ability...for what? I see cheap cameras out there advertising 12 Megapixels as if that is all that counts in your selection...NOT TRUE today as it was not true in the days of film....No one expected a professional finish from a Kodak Pony camera! The lenses were cheap.
Today, you cannot judge a camera by Megapixels, period! You have to consider what the lens is, who makes the camera (reputation), and how they make the camera.
In today's market, very few are willing to pay 5,000.00 for a camera body...other than professionals, and even then, the professionals will tell you it ain't the camera that takes the picture, it is the photographer. IF the photographer has a very fine tool, then the pictures will be very fine.
As in the past, probably Nikon stands out from the pack, followed closely with Canon (Canon has improved their lenses greatly, but they still are not Nikons. Nikon, to stay in business, produces cameras (SLR for the better photographers) from abut 500.00 to 6000.00 or so. Obviously there is going to be differences, but what do those differences mean to you? Probably nothing. A professional photographer can make a Nikon D40 sing! An amateur cannot take a really fine picture with the best of cameras...so it comes down to experience, finesse, what have you. Once you pass that 6 megapixel mark, it is the lens, the machine, and the user that makes the difference.
I suggest you go into a camera shop, try out camers...you will soon find that I am correct.
I own a Nikon D90 (superb camera), a Nikon D300S (over the top with features, and ability to handle difficult lighting) and a Canon point and shoot G-10 (they don't come finer than this little camera for what it is!
I hope this helps in what you are looking for. I hope Fotoace chimes in on this one. I suspect he will agree with me. I do not list a bunch of links here, for I doubt that anyone asking is going to check things out...and even then, it is opinion. I am comparing today's cameras with the finest of film, used for almost 1/2 century in its finest form.