Depends on what I'm shooting:>astro>night shots in realy dark places>macro
Manual, the metering doesn't realy work that well in extremely dark conditions or with my frankenstein macro lenses.
AF or preview often doesn't realy work either in these conditions.>landscape>portrait>most stuff in general
Aperture priority, I can adjust the desired depth of field and don't have to worry about shutterspeed.
If required I set it to over/underexpose.>sports>fast moving stuff
Shutter speed priority with variable ISO.
Generaly I mostly use aperture priority and bump up ISO when my shutterspeed gets too low.
Having a rather steady hand allows me to use rather slow shutterspeeds of 1/(focal length/2) as a rule of thumb on a crop sensor with no IS.