It depends a bit.
Landscapes, and other slow action shots - full manual
General walk around shots, Av with a low ISO.
For wildlife and fast action, I find myself using Shutter preferred with auto ISO more and more. I find too slow a shutter speed more damaging to a file, than a higher ISO. I can reduce the noise from a higher ISO, better than I can sharpen a file blurred with too slow a shutter speed, and for BIFS I really want a minimum shutter speed of 1/1250th or faster. Modern DSLRs do fine up to ISO 1600 if you do not under expose your image in RAW... Even m4/3s bodies.
JMHO