Basically, it comes down to two things if your gonna go all in on a bet...
First off, I'd make sure your very knowledgable about MMA, and about the Fighters in the bout especially. After that, If your feel comfortable with your knowledge, Trust your Gut. Be careful about second guessing, because that's how you end up kicking yourself if you had it right the first time...
If those are the two fights your thinking of using, though, I'd go for the ALexander/Sakara one, because first off, you gotta have some big stones to go all in on either Henderson OR Rampage, that's a pretty damn evenly matched fight In my opinion.
Now then, Onto Houston and Sakara: Sakara has good stand up, But the two guys he's beaten have a combined UFC record of 1-8, and only finished his last fight with his strikes (again, his strength) against a guy nobody heard of before, and probably won't hear from again. Not to mention, Sakara's Chin has to come into question after he got knocked out by Mcfedries, a true Middleweight. Granted, McFedries hits hard, But Houston looks more technichal and hits just as hard, if not harder, that McFedries, Not to mention Houston is naturally quicker and pushes a faster pace.
As for Houston, Yeah, He's had one fight, but It's arguably One of the most dominaunt wins this year in a fight against someone who was considered a contender for the belt. Plus, if you check out other sites and hear trainers, fighters and scouts talk about houston, they never have a bad thing to say about his skills, trainer, or his heart. ANd if you read houston's interviews, my gut feeling tells me this isn't a guy who loses to someone like Sakara. But that's MY gut feeling.
ANyways, yeah, I'd Place it on alexander ahead of Hendo....BUT, I still Think Matt Hamill is gonna be UFC 75's Patrick Cote if you REALLY wanna take a risk
My thoughts...Take them for what they're worth