I like the reducer caps. They take away my fear of accidentally tipping over a bottle and spilling everything because the reducers act sort of like a "dam".
With the reducers, I can actually control the amount of oil I want use drop by drop. For thick oils like Snake Oil, I tilt the bottle to the side for a little bit and wait for the oil to get through the feeder tube and when it's close, I put the bottle directly against me skin and use just a drop. So, for me, it's really convenient.
I also like the idea of dropper tubes. Or caps with wands attached.