If I were in this, I'd have to be right at the beginning of the row, because I'm leaving on the 6th of august for a trip to Canada, and may not be able to check the boards for at least a week... so I'd need to get my contribution out of the way quickly.
Style? Doesn't matter, although the main preference I have for ISWorld.sty is that I made the terrains to complement my own design style for levels. That said, i don't know how it'll work with other designers, although it appears Isu can make neat levels with it (Or, the one I saw, at least).
If we are going to use a Juanjo style, I like Galaxy.sty or Machine.sty.