nooope akira. Second one, and I'm 100% positive on that. The first one will have a relatively strong, yet isolated straight current, from the outflow to the inflow. The corners and sides won't really get hit with flow, and it just doesn't work out. It may look like in theory it would work better, but it 100% does not. Have them on the same side next to each other creates CIRCULATION (circular flow, duh) as the water exits near the surface and enters near the bottom, going round and round. Having them on the opposite sides provides almost no circulation, and simply creates a flow in one direction like a stream. Not only is the flow incorrect, but the transfer of gases like CO2 and O2 is done incorrectly. Plants, fish, and everything in the tank needs water flow and circulation in all directions in order to function properly, and the first diagram merely shoots it all in one direction.
Also, take a look at all of Amano's tanks, never once will you see a filter arrangement other than diagram #2. HTH
Suspended for 30 days for being terrible to other members