African Tiger fish swim really fast, Height dont really matter much, most importantly is the Length. 6' or 8' tank is good.
I always thought Height creates more pressure thus will promote growth of the fish. I read this some where but not sure is it from reliable source or not.
As far as my knowledge goes, oxygen, water quality, temperature and water pressure contributed to the growth of the fish.
This I agreed with you.
But you have to think about what kind of fish you're keeping. Fast and long swimmer like long length tank. Rays like wider tank, its all depending on fish.
However, not everyone can but bigger tank is always better for the fish. Not everyone have space for big tank.
From what others have said, GATF have the ability to grow to 3ft in home aquarium so the wider the better.
Overlooking the height is a mistake.
I keep rays and have short tanks. I KNOW how much fish hate not having height between them and the rays.
IF there are ZERO plans for rays you're good, but if planning on having rays I'd factor that in to the height........