[nereefpat]

The megaflows make aquascaping really difficult, as mentioned. That is the worst choice of the three.

Of these three choices, I would get the single corner overflow in the left corner, away from the viewing side. I would go against what you said, and make it a Herbie. A single drain won't be able to handle much flow without noise, unless the hole for the drain is large.

Why not go over the back with the return?