If the snake is eating, shedding, and evacuating regularly a snake can be just as healthy in a tank as a tub. I own both but I honestly feel alittle sorry for the ones in a tub when I have tanks like this.
Both have their place but I also prefer to make a display of my enclosures. If I had the money and space every snake would be in a nice presenting cage with all the trimmings.
As to the topic at hand I prefer cypress mulch. I have used it for a long time. A few months back I wanted a better look in my tanks and decided to mix Eco Earth, Repti Bark, and Forest Floor cypress mulch for a more natural look. I really like it. It has a great texture and look while holding moisture great. Eco Earth alone can get a tad dusty once it starts to dry and mixing it with the other two keep it in check. In my tubs I use straight cypress mulch. They hold my younger bloods and they like to borrow in it. The Eco Earth gets stuck in their pits so I don't use it with them.
The first two pics are the mixed substrate and the last is an older one of straight cypress mulch.