When I think about best designers from a technical standpoint, Phyter, Buster, Hansixx, and Real are the ones who immediately come to mind as those who have always been on the creative edge, and will always be the big four core designers. I'm a huge wooden coaster fan, and I always love great support work, so I'd have to say that a lot of my favorite coasters have come from people like nightride from C2k and, myself, lol...but at the moment, I really like Master Pi for taking Intamin Fan's original layout and really creating an excellent ride in Nanosuelta (hope that's the name), combined with Bobcoaster's excellent support work. It isn't the most technically perfect, it doesn't have elaborate scenery, but it's just a damn good ride, so I guess those guys are my favorite designers at the moment.