"What do the rest of you think? Is there a strong correlation between rationalism, giving knowledge high intrinsic value, and giving art low intrinsic value? If so, why? And which would you rather be - a great scientist, or a great artist of some type?"
I've read through many of the posts on this site, but this is the first I've answered--the first I've felt knowledgeable enough to answer.
Generally speaking there might be a strong correlation--I've seen that pattern often (I'm currently in medical school, and in undergrad was the only LibAr in a houseful of engineers). There is, especially in the West, a dichotomy drawn very early and very deeply between imagination and knowledge--a belief that somehow they must be mutually exclusive. Even Einstein (who really ought to've known better, since his imagination was fundamental to his attainment of knowledge) emphasized the distinction ("Imagination is more important than knowledge"). Most forms of higher learning demand imagination and discipline; artistic creativity demands them as well, albeit in a different tenor.
I'm an artist, and my high valuation of knowledge (and growing valuation of rationality as a tool with which I can temper it) interlocks seamlessly with my desire to create. A greater understanding and integration of the world, more information, more finely honed perception--all of those things increase the quality of both my life and the things I create. This is as true of the areas of physics and mathematics and cellular biology as it is of English literature. Greater understanding produces better art.
It's doubtful that I'm a singular, or even rare, instance of such thinking; many of the Renaissance masters would probably agree. I've often wondered what Michelangelo might have produced if he'd somehow been able to share in Mr. Yudkowsky's beautifully elaborated HPMOR vision of humanity triumphantly ascendant over death and mourning; I suspect it would have outshone his 'David'. In fact, Mr. Yudkowsky's a great example of someone who feels no need to choose between artistic achievement and profound knowledge.
As to your question of preference...I can't choose. If I were offered one of the two, I'd seize each as eagerly as the other. And--like Goethe, Franklin, Khayyam, da Vinci, Pascal--if offered both...I'd choose them both.