I’ve been asked that dreaded question again:
Q: More Mega-pixels is better, right?
A: Sure, if you can afford an H4d-200MS or 645DF & IQ180 Medium Format…with a lens or two.
Q: What’s Medium Format?
A: * Sigh * 
Nikon Canon Nikon Canon …
Has aggressive marketing and consumerism made potential DSLR buyers really believe that N is better than C or C better than N thanks to the Mega-pixel count of the latest release? Are Mega-pixels the be all and end all buying factor of the perceived quality of a digital camera and thus the only basis for a purchasing decision? It’s as bad a question as the “What camera is better? Nikon or Canon?” Define “better”?
What about Sony, Sigma, Pentax, Kodak, Olympus, Fuji, Samsung, Panasonic, Leica, Hasselblad, Phase One, Mamiya, Zeiss etc. Are they no good? Never heard of them? Won’t consider them?
Sensor Sizes (Not to scale) Image courtesy Wikipedia. Click on the image to go their comprehensive sensor article.
What about the actual sensor dimensions used in various iterations of all these brands and cameras?
What about the TYPE of sensor, the design and the technology of the actual sensors that record the image? There are many different types of sensors each with their own unique design and improvements over the years. How does the manufacturers in-camera image processing software algorithms shape up? Do you need to shoot low light without flash? Are you only shooting in natural light. Wildlife, events, PJ? How about studio work?
Are lenses/glass quality also not part of this equation? Do you want one lens that goes from wide angle for landscapes to 600x zoom for spotting the tick on a Warthog’s butt at 200 meters? It’s ok, it’s got anti-shake! Will it still be as sharp on a P&S 600mm 12Mp with 1/1.8″ sensor (24.7mm²) as on a full frame 24Mp with 600mm f/4? with a 35mm (370 mm²) sensor? What about the signal-noise ratio? The larger sensor also has less clipping.
Based on ones need, I can make a purchasing suggestion wrt body, make, model, lens and sensor type/mega-pixel choice. It’s about the intended use, not only the Mp. Get a FF DSLR and the 4 or 5 lenses you will need to go from Ultra Wide Angle to Super Zoom at 800mm. Now try sneak it on as hand luggage on your way to the Serengeti.
There is not one definitive answer unless money is no object. Note that these two cameras are used in mostly studio and product photography and may not be ideal or practical for wildlife, astronomy, your next fishing trip (or event work?) due lens selection and body size, practicality and even weather resistance:
Who here has seen (drooled over) the Hasselblad H4D-200MS yet?
Hasselblad H4D-200MS – CCD based back.
Or the Phase One 645DF with IQ180 Digital Back?
Phase One 645DF – CCD based back.
In order to answer the More Mp is better question:
What is your intended use of the camera? (Holiday snaps to billboard advertisements of supercars/models).
What print size do you want? (Postcard or a wall mounted A1 Canvas?)
What is your budget!? (How deep are your pockets?)
Have you got old AF or MF lenses from the film days and what brand? (Saving money on glass allows you to spend more on new body technology)
How big are your hands and how strong is your back? (Good glass weighs a tonne)
You can see where I am going with this… (more…)
