In terms of contrast ratio and black levels, the Sony and JVC are always at the top of the list. The Sony's use a dynamic iris, where it may be distracting every once in a while. But their iris is supposed to be better than just about any other manufacturer's implementation. JVC is able to get very similar contrast ratio and black levels without a dynamic iris, which is a nice plus. For the past several years JVC has nudged ahead of the Sony in terms of professional reviews. But this year the Sony nudged ahead of the JVC slightly. I don't think that you could go wrong with either of them.
For me, when I go with a projector it will probably be either the Sony or the JVC. Contrast ratio and black levels, to me, are the most important aspects of a display to give the most life-like image quality (that is unless something else like color, for example is waaaaay off and cannot be fixed with calibration). Now having owned a Kuro display for the past several years, I cannot change this requirement when going to a projector for a larger more immerse viewing experience.
If the Sony and JVC are out of your price-range, then the Epson UB's are supposed to be close in terms of contrast and blacklevel, but a more budget friendly price-point.
