Well the thing is Anderson Silva vs. GSP has all the potential in the world to be a snooze fest. Seriously, both guys are making a living currently on going the distance and not really giving it their all in the cage. I love GSP, he was a great title chaser but as soon as he won the belt he got a lot more boring. Look at it for yourself. His fights as a challenger were a lot more high octane and he finished a lot more often. However, since becoming champion his only fight not to go the distance was his fight with B.J. Penn because Penn's corner threw in the towel.
Anderson Silva is exactly the same. An exciting fighter who after becoming champion became much to safe. He finishes non-title fights but goes the distance in all the rest of his fights.
Personally, I have little interest in Anderson/GSP. I won't say I don't want to see the fight but it certainly is not on my dream fight list. It just doesn't scream out exciting like Rampage and Rashad does.
Rampage and Rashad have some genuine heat between them. They also both fight every fight to knock their opponent out. There fight has a ton of hype surrounding it and quiet frankly will be exciting to watch. While I don't see the fight ending early I do think we will see 15 minutes of two guys beating the holy hell out of each other. So to put it simply, I would much rather see Rampage/Evans and think that it has a lot more potential as a fight.
I have to disagree highly with your assessment. In terms of hype, GSP vs Anderson Silva is by far more appealing to the hardcore fans, and to the casual fans. Every one knows how dominant both champions are at this moment, so there is no question on which match up would be bigger.
In terms of actual match quality, once again I would say GSP vs Anderson Silva would be much more appealing, let me break it down: At this point, GSP is able to take down any opponent at will and beat on them round after round. Anderson at this point is able to do literally
anything he wants with any opponent. Anderson has also shown to be able to handle strong wrestlers, evident in his fight with Dan Henderson, whom he out-wrestled and then choked out in round II. What ever happens in this match will be exciting, whether GSP can secure takedowns and
nullify Anderson, who whether Anderson can toy with GSP; both of these situations would be absolutely unprecedented.
Looking at Rampage / Rashad, this match
needs the bad blood in order for it to main-event. In my opinion, this is a weak main-event, and the weakest UFC since 109. Rashad is coming off of a devastating loss to Lyoto Machida where he did not eve look competitive, and Rampage is coming back from more than a year lay-off, and his last fight with Keith Jardine was very lackluster. To me, this match does not deserve to be a main event, and I think you will see this one go the distance.