I have several. I have a Gerber Diesel, simply because it was issued by my employer. It's OK, but not great. My usual carry multi-tool is a Leatherman Skeletool, because it's light and has just enough bits to do most of what I usually need (aircraft mechanic) without having too much. I also have a couple of SOG multitools including my absolute favorite multitool, the (now discontinued) Tool Clip.
I stick to either Leatherman or SOG anymore. SOG is nice because you can buy different tools to customize your multitool(http://sogknives.com/store/components.html), and their multitools are built like a tank. Some of them are also compound leverage, making cutting and holding on to things easier.