I am in the minority here, but I went with a 150g xtall (48"L x 24"D x 30" high). I prefer the height, the longer tanks always look cramped to me. If you are going to pile rock the entire length of the tank then maybe the longer is better, but if you try some kind of landscaping you may have more options with the taller tank.
What about depth. Not tallness but width from front to back. I feel that 18" for a 150 is really cramped. In other words, is length more important than width?
What about depth. Not tallness but width from front to back. I feel that 18" for a 150 is really cramped. In other words, is length more important than width?
It depends on your budget and taste. For my budget, I could get a 48" long, 36" wide 200 gal tank, or a 72" long 18" wide 150 gal. I went with the long rather than the wide.
48x24x24 - 120 gallons is a popular size. It gives plenty of depth (front to back) and is not so tall that your armpit is in the water when you need to reach the bottom. The next size up: 72x24x24 - 180 gallons, is what I have and I love it. 6 foot is the right length for larger fish to swim in and the depth gives plenty of open sand space in front.