Call me old-fashioned, but I prefer the deductive method of teaching grammar. To me, it's the most straight-forward and easiest way to explain grammar rules. First you explain the rule, give some examples, then practice. There is no guess work, no wasting time trying to figure out what is going on.
In my experience in learning both French and German, the few times that the inductive method was used almost always ended up falling back on the deductive method because the rule being taught was not immediately apparent. This was most prevalent in basic and beginner classes. Beginning students are still struggling with the meaning of basic words. Why have them guessing at grammar rules?
The inductive method has its place, but my thought is that it is best left to more advanced classes where the students have a better feel for the target language and are more adept at discerning what "sounds right" or what "sounds wrong."