i did ninpo for a long while, just took it up again, great martial art, but only in that it works for me, did some wing chun too, liked it a lot, they seemed really straight forward and practical, almost, sciency, treating body parts as levers, apply pressure here against the direction mobility etc appealed to the engineer in me
but you have to try loads, and there's no one best one (except mine :P)
im also interested in silat/kali. if you watch the bourne films thats the "style" that was used
ninpo is ninjtsu, but don't believe all that wearing black, mystical esoteric powers cr@p. the real ninja were peasants in mountainous and forest regions. they weren't assasins either. more like intelligence gatherers. think er.. SAS, can raise all hell but prefer not to even be seen inthe first place.
its brutal and nasty and doesnt look fancy in the slightest. it also isnt for everbody, there's no quick results and it can take 8 years plus to reach Dan. you wont be walking into the street and kicking peoples arses, in fact you can get thrown out for that.
stick at it for the long haul and you'll find your less likely to get into fights and more likely to avoid them. this is a good thing :)