Corsair K60, with Red Switches. I've never really tried other switches but took Red for its low actuation force. K60 was because it was the cheapest Red Mechanical Keyboard around.
I have a problem with maintaining streams and while I'm still not exactly good at it, using red switches has almost doubled my ability overnight because it's just so much easier to press.
Though, the keys I often use (WASD + E because I play with W/E) have become quite dirty, and I've only used it for a rather short while. The letters aren't fading off, but they look much darker. Other Red keyboards may be more suited for you, if you can afford them.