I think you are all looking at style and substance and only looking at the differences between them.
The simple fact is, they go hand in hand...you can't have one without the other unless you go to very great extremes.
The trick comes in in how you blend the two together, to create the effect or impression that you are trying to achieve.
Which will determine how much of either you wish to go for.
I don't preffer either, I can jump back and forth between the two rather easily, since I use them as tools, and don't see them as limits.
Neither is better...and both together will work much better. at least from an artistic standpoint.
Artistically speaking, none of us should be at useability over style, or else we should all be engineers.

But as I try to imitate life in a lot of my work, I have to conceed to substance quite often. WHen used in conjunction with style, that is when your best work will come through.
And style and substance are very general terms as well...as each has tons of subcatagories.
Basically they are both just tools in my opinion, there to be used as you see fit to gain the properaspexts in whatever you are trying to create..and neither has to take away from the other. THey can be harmonious...you just have to first be willing to use them to you benifit, and then learn how to use them.
Just my two rambling cents

Rob