My tank is 6 feet long, 24” wide and 30” tall. I absolutely *love* the 30” depth and wouldn’t change it for anything, but I will warn you that it can be kind of a pain too. I can barely reach the bottom of the tank, especially the bottom on the far side... I have often wound up putting my nose in the water as I try to reach something on the very bottom of the far side of the tank. I have a set of 30” grabbers that I can use for some things, but trying to glue corals in place is something that really needs to be done by hand and can be a pain toward the bottom of the tank. Like I said, I love the extra height and I wouldn’t change it, but do be aware of what you’re getting yourself into.
The 24” width is also nice to give a lot of space for swimming room in front of the rocks without making things feel crowded. I’d have a really hard time trying to choose if I could only pick one.... 24” width or 30” height.
If you are looking at glass tanks, the other thing to consider is the weight. Like I said, my tank is 72x24x30 and my tank weighs over 400lbs empty. It was a real effort to get my tank moved from my garage to my living room and I can’t even imagine trying to get it down a set of stairs that it barely fits through.
Oops, I meant 30" in terms of width... ie the tank would be 18" 'deep' from top to bottom and 30" 'deep'/'wide' from front to back. However I still think your comment stands because reaching towards the back of a tank configured as described would also be a challenge, especially at 8' trying to reach the back middle!
The tank itself will be acrylic for that purpose -- it would be an incredible challenge to get a heavy glass tank squeezed through my condo and down the stairwell -- I seriously think it would end up in injury or a broken tank or foot! The acrylic should be significantly lighter and actually more affordable through the supplier I am working with.