Intelligence in conjunction with wit. ;)

I find the most attractive feature in a partner to be when they are correcting my use of words, and or asking me about word usage. Like, WMD, "How do you use the word "white" without re-inscribing racism?" Also, those who can play a good game of scrabble always catch my eye.

I fall for people who respect me. That's hot.

Kindness.

I would have to go with intelligence although "intelligence" can be a tough concept to nail down. For me it's a curiosity and interest in the world around us coupled with the ability to discuss them without feeling the need to use knowledge to beat down others.

Not entirely sure I could narrow it down. Intelligence is absolutely essential, but so is kindness, a compatible sense of humor, respect, etc.

Intelligence combined with kindness and interest in others. On its own it can be a cold, unwelcoming characteristic.

Paying attention. It's the broadest statement I could find to encompass respect, kindness, appreciation, etc.

Well, intelligence has historically been the 'dealbreaker' but I do have a list of things that rate highly. Of course, I also make sensible 'compromises' rather than reject someone simply because they 'fail' a checklist.

I know it sounds like a recap of statements above, but intelligence is essential, as well as a kind and honest heart, being interested in the goings on of the world around us, and having interesting thoughts about it.

As often I think Sharper has nailed it best: his description combines intelligence with kindness/compassion/empathy. It reminds me of some Sherlock Holmes videos we just re-watched last weekend. Holmes, as played by Jeremy Brett, is intelligent to an extreme degree, yet it also rude, arrogant, contemptuous and totally lacking in empathy for less gifted mortals (such as Watson). Not sapiosexually attractive.

In case you're wondering, after these comments - yes, I have been a Sherlock Holmes fan since I was ten and always will be. (And Jeremy Brett rules as Holmes - read one of the stories, then watch the Brett video - perfect! After I discovered Brett, I can't watch anyone else in the role).

Exactly what sharper said, coupled with warmth and compassion. Those are absolutely irresistible qualities, to me.

I think that is why the modern-day Sherlock Holmes, Det Robert Goren in CSI, is so much more attractive. Although they based the character on Holmes, but with more of a psychological skillset, they also made him this rather haunted, empathetic character who can often identify with the perpetrators.

I'm going to have to agree with mytwocollies here (like that's a surprise).