For looks it depends upon the height of the tank, but when I had my 60 cube, 2' high, I had a high stand, 34", and the viewing was really nice, and with it being high, you got the full view of the tank.
That being say I think you need to take into considering a couple of things on the stand height, the first being the amount of room under the tank, as you want to have good access and you need to take into account the height of the skimmer. The second thing is if the tank is high, say 36", you need to take into account the access to it from above, so you may need a ladder or step stool to access it.
mine is 42" on a 120g tank harder to work on but i dont ever really need to work on tank atleast going into tank, great for a bar stool in front of it looking at tank or standing because you dont really have to look down
I agree with josh. Height of tank will also affect the height of the stand. I m 6’2 and built my stand 36” and my tank is 24”. If I would have gone with a 20” high tank I would have made the stand 40”. So I think it is a question of how high do you want the whole set up to be?