I'm thinking between the couture vs. machida fight their takedowns and takedown defenses are going to pretty much cancel eachother out. I'm picking machida because of his elusiveness and explosiveness in his ju jitzu. Randy definitely has the advantage against the cage because of his dirty boxing. Getting Machida there will be his biggest challenge.
Shields vs. GSP, I'm picking GSP. The guy is probably the most technically and mentally sound guy in MMA. He has no holes. The only way I see GSP losing that fight is by knockout.