Depends on what you wanna do. Shadow clones are the easiest to make, wood clones are the tougest, zetsu clones are just plain creepy. Shadow clones are personally my favourite.
I'd go with shadow clones for recon missions, this is due to the fact that they can dissipate at the whim of the caster, or for overwhelming numbers. These can also be useful for fast, one time attacks. Ex: Naruto's rasengan/rasenshuriken, or Kakashi's chain of lightning that he uses in the jinchuriki battle.
For a lengthy battle, wood clones seem to be pretty tough to get rid of, they seem to just regrow lost parts. (Not counting chakra levels because three people can use it and one has a much lower chakra level and one has a doujutsu to contend with at the same time, results would be inconsistent). Wood clones would also be useful for gathering intel on a recon mission in a forest type environment.
For multiple opponents and desiring a shorter battle, zetsu clones seem to have the highest consistent chakra level, therefore they would not be draining chakra from the original. This would allow each of the clones to fight at full strength.
Water clones are good for taking a hit, they can just reform or dissipate. They are also good at hiding in water (go figure -.-), this can be useful for recon in certain types of terrain.
Regular clones are pretty useless except as illusions, I doubt that anyone would use these in a real battle. It hasn't been shown since...Sakura and Ino's fight in the chuunin exams.