I have holes in both my A Pillars, one from the antenna (it's now removed), and the other from.. I don't know what was ever there. But that is where I have leaks. The water runs in and drops down from behind the kick panels.
I also have water coming in from my back window, but that's because my window rubber is cracked and falling apart.
You might want to take off your cowl panel and clear out any debris that might be in there. If it's really clogged with leaves and debris, the water can collect and get high enough to drip from your vent tubes.