Dvorak. I switched back in 2005 from qwerty and never looked back. I never looked forward either, so I may try out Colemak at some point in time. Workman looks solid for English, but I am not a native English speaker.
I tried dvorak in 2008 and was using it for about 6 months. The thing that really tripped me was the keyboard shortcuts. I was just too used to the QWERTY setup. Did you have to overcome this, and if so, how?
I think I always thought about shortcuts as consisting of their constituent parts, rather than a key shape that does an action. So when I switched, my brain still thought Ctrl+c, C just moved