I'd put them in the middle. I use filter current to aerate my tanks, not airstones, and ime they neither particularly seek out or avoid the filter current, comfortable either way. Where they hang out in the tank is more about other fish in the tank, rocks or driftwood spots they like, etc, so I've had them hang out (or spawn) right by the filter or at opposite ends of the tank. One way or another, though, I'd say they want good aeration.
...Or, if this is what you're asking, filter current is sufficient, they don't need a whirlpool.