My vote is for the 20-25 MP range, the lowest of all the other votes so far. I am happy to trade off high MP numbers for a sensor that gives me great performance in low light, like the 18 MP sensor on the 1DX. The fact that I can shoot wildlife at ISO 1600 and get a nice fast shutter speed with zero noise is a sheer joy. If I have to go higher than that then I can easily apply noise reduction in Lightroom, but that always comes with a loss in sharpness. If you have lots of light and a subject that sits still (and you use a tripod), then you might be happy with a high-MP camera. Otherwise, like Neuro said, there is the law of diminishing returns.