I would say Super AMOLED Plus hands down. It's true that the AMOLED displays portray images more vivid and with very deep contrast, but I wouldn't say that the colors are unnatural, in fact I find it to be a major advantage of the 7.7, it will make movies that much better. The Super AMOLED Plus displays also don't have a backlight so they are much thinner and use less power. This is technology much more advanced than the panels in today's TVs. The Super PLS displays Samsung makes (what the 7.0 Plus has) are also very good, some say better than the IPS displays in tablets, but it's still an LCD, not quite as good as the Super AMOLED Plus in my opinion.
Also do not forget that the 7.7 display is higher resolution at 1280 x 800, the 7.0 Plus is 1024 x 600, and in my opinion it will make a big difference especially in Honeycomb. But don't let any of us persuade you in your decision, if you can, go look at them side by side in person and decide for yourself. We don't know what the 7.7 will cost yet, but I imagine the 7.0 Plus will be cheaper so if that is an important factor for you then it wouldn't be unwise to consider it.
As far as other specs go, the 7.7 is a bit thinner and lighter and has a bigger battery, a slightly faster processor, and a 64GB option.