Although I'm aware that intelligent, incessantly cheerful, perky, bouncy women do exist... I certainly have never seen one. And intelligence is the #1 thing for me, followed very closely by compatible principles and outlooks on life. Which, seeing as those are all based almost completely on logic and reason, tend to exist with intelligence. Though certainly not always.
The above notwithstanding, I'm fairly certain an incessantly happy person would irritate me to no end. Happy people like to talk and interact, and that's rather abrasive to my need for solitude. It's not bad in small, controlled amounts, but constantly? No thanks.
Also, T-Bone, happiness isn't something you can choose all the time. My emotional state tends to remain in the emotionless range, unless I'm studying an interest at the time, at which point I can be called intense. Ignorance is Bliss, and it holds true, most of the time. Knowing what I do about the world and human depravity and being unable to stop thinking makes being happy somewhat of a problem. It when I'm able to not think about those things, IE: be ignorant of them through not thinking about them, that makes happiness a possibility.
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I am Jon Stewart with some Colbert cynicism, Thomas Edison's curiousity, wrapped around a hardcore gamer sprinkled very liberally with Deadpool, and finished off with an almost Poison Ivy-esque love/hate relationship with humanity flourish.