A mix of both IMO is good.
I know Jeremy asked this the other day, and Tom I thought agreed that coming UP from the substrate was ideal. Do a search and read that thread........
For me, I have 6 loc-line outlets, and 2 koralias, pointing in all directions.
I seem to have good growth and very little algae in all areas of the tank, and light is much less in ends, due to MH, so I think the flow helps a lot in these more remote areas.
I can see good movement of leaves on any plants.
However, coming from the bottom, would give the max time for ascension and mixing on the way up. Plus, if mist exists, will give more time to get caught in the leaves...........