I would personally also count architecture and literature in my definition of 'fine arts'.
For me, it's a close call between ALL forms of art, but -as much of a cultural philistine I remain-, the one that wins out BY A NOSE, by a slight margin, would be painting.
I love music, but I could never understand music as much as I understand painting. I watch someone perform, whether a band, or a solo instrumentalist or singer, and I'm in great admiration of their skill as well as of the emotional message they're conveying, but seeing as how I've never mastered a musical instrument, and sing like a crow with laryngitis, music is always something of an alien thing for me.
Whereas, when I look at a painting, it's a lot easier for me to trace the process from its conception through its composition... and the emotion that would be connected to that. This may sound outrageously conceited, but whenever I'm in an art museum, I've more of a feeling that I'm looking at the works of 'brethren'.
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clarity of thought before rashness of action