If getting accurate flesh tones is a key to your satisfaction (who wants flesh tones that are too ruddy, or too anything), in the catagory of color accuracy for movie watching (or anything in a darkened room,, the Panasonic is the winner. Now, of course, you can have both of these projectors professionally calibrated, and no doubt get almost identical results, but who's going to spend $500+ to calibrate a $2000 projector?
Viewed side by side, the Panasonic is the immediate - though slight - winner in color accuracy, out of the box ! Buy a easy to use calibration test disk (no tech skills needed), and invest an hour, and both projectors will produce superb color.
For DVD viewing (or Hi-Def movies) I preferred the Cinema1 or Cinema2 settings on the Panasonic (Cinema1 is probably, technically the better setting, but I preferred Cinema2 with its slight increase in contrast). On the Sanyo PLV-Z4 projector, I strongly preferred the Creative Cinema over the Pure Cinema setting.
Picture Quality - Black Levels - Shadow Details - These are often referred to as the "Holy Grail" of home theater projectors. Those big, old, ugly 3 CRT projectors can do pure black, but DLP and LCD projectors cannot. The result - pure blacks come out dark gray, and therefore in scenes that are supposed to be very black slightly lighter details are lost as they all come out the dark gray. DLP projectors are inherently better than LCD projectors, in getting closer to being able to produce black, but new LCD projectors like these two, use lots of fancy technology to improve importance, like dimming/brightening the lamp frame by frame, having a dynamic iris in front of the lens, and "AI" ("articifical intelligence) to overall adjust the image to enhance black levels and retain shadow detail. A quick judge of performance in these areas is the contrast ratio, but due to the "smoke and mirrors" technologies I have just mentioned, that can now be misleading. A DLP projector with 4000:1 contrast can do much better "blacks", than either of these with their 5500:1 (Panasonic) and 7000:1 (Sanyo) claims.
Enough explanation. Again, with a full calibration the results will change, but out of the box, I found the Panasonic to have the advantage here. Immediately below is a side by side (Sanyo on the left) you can see an opening scene from Star Wars - Attack of the Clones. The Panasonic definitely displays far more stars than the Z4. (The Sanyo projector is in its best mode, Creative Cinema, the Panasonic projector in Cinema 2). If you get up close, not only can you see that the Panasonic has more stars, but that they are a bit brighter, yet, in the lettter box area along the bottom of the screens, you can also see that the blacks in there are almost identical (yes the Z4 is slightly bluish). The result is the Z4 is losing more shadow detail than the Panasonic projector. The second side by side is slightly overexposed so that you can see the differences more clearly. (Note, the Auto Lamp Iris is turned on, on the Sanyo - that will be discussed later.)
On the Times Square image, look at the dark building on the left (partially cut off on the Sanyo (left), and the the tall dark building about 3/4 to the right near the top. Again, more detail on the Panasonic PT-AE900u projector. On the image below, look at the detail on the right side of the Chancellor's face.
Picture Quality Modes - Handling higher ambient light conditions. Both projectors offer a wide array of choices in presets, with names like Cinema1, Livingroom, Dynamic, etc. As mentioned above I liked the Panasonic's presets better for typical viewing in darkened or very near darkened rooms. In rooms with significant ambient light, the Sanyo offers more choices, but all of these "bright modes", inherently sacrifice the best possible image for increased color saturation, contrast, brightness, etc. Sanyo has more choices, which is a plus, but I found the two projectors more similar when using the brighter presets.
No particular winner here. However, the Panasonic AE900u projector does appear to be slightly brighter, at its brightest, (very slightly) which has to count as a plus for it, over the Z4 projector, if you have challenging levels of ambient light, Yet at the same time, Sanyo's most tricked out mode does cut through the ambient light better, but the image quality (color, contrast, accuracy, etc.) is slightly poorer. In other words, these projectors are about tie when it comes to their brightest modes for dealing with too much ambient light.
Picture Quality - Intermediate modes - Watching TV, Sports . These are slightly brighter than the Cinema modes (Family room, etc.) and designed for non-movie viewing, sports (who wants to have friends over and watch a football game in pitch blackness) and dealing with modest ambient light. Both projectors performed well in these modes, but the Panasonic still had more accurate colors, giving it a slight edge.
Picture Quality - Low Res TV (and VCR)
While I have tried to pick apart all the differences between these two fine projectors above, they are really very close in almost any area of performance. Here is one area with a huge difference.
If you are watching regular TV from cable/satellite/antenna, you will find that the Panasonic PT-AE900u does an excellent job (considering the poor image quality of the source). The Sanyo is another story. It is suprisingly poor on regular low res TV. So if you will be using your projector for a bit of everything (hey, how many Hi-Def channels do you have?), the Panasonic has a huge advantage. I recall watching SportsCenter, and seeing Tiger drop a 20 or 25 foot putt, and for the most part, the ball looked almost square! (Screen door effect also probably lends severity to this problem (see later).
The Panasonic projector, is simply better at regular composite sources, much better. Sure this programming is significantly inferior to DVD or Hi-Def, but many of us watch plenty of it. Whichever projector you choose - remember the old adage: Garbage In (composite TV), Garbage Out! You aren't buying these projectors for "standard" composite TV. By definition, your huge screen, is just too big to provide a good image with such a low resolution source. The same is true for most Big Screen TVs.
If you plan to watch a lot of regular TV, this is one of the areas where there truly is a big difference and the PT-AE900u is the BIG winner. (You may recall, the Sanyo, on the other hand, is "slightly" sharper, on DVD, and the two are pretty much "tie" on Hi-Def 1080i source material.