I started with fly sparging, and tried batch sparging a few times to see if I could save some time on brew day.
Batch sparging was slightly faster, but I lost about 5% in efficiency, and I found it more difficult because I wasn't used to it. With my 5g MLT, I couldn't brew a 5g batch with an OG > 1.060 with a batch sparge, whereas I could get up to 1.075 with a fly sparge.
If I didn't have a false bottom, I would batch sparge. The one thing I did that improved my efficiency considerably (with a fly sparge) was a mash out by adding some near boiling water and stirring it in really well before starting the sparge, raising the grain bed temperature up to about 165. This increased my mash/lauter efficiency from 75% to 85%
-a.