I\'ve been using either Pig or Java for Map Reduce exclusively for running jobs against a Hadoop cluster thus far. I\'ve recently tried out using Python Map Reduce through the H
Regarding Java vs. Pig - I'd use pig in most cases (along with Java UDFs) for flexibility and for letting someone else (pig) to figure out what the best way to split the job in to maps and reduces, combiners etc.
I use Java when I absolutely want to control each and every aspect of the job.
Regarding the use of python (or other langs) that's something I'd use if the developers are more comfortable with these other languages. Note that you can also mix pig and streaming