Ok, since I'm expected to pipe up here...
BPnet's Official Tank Advocate 
These are my Personal opinions based on my own experiences.
TANKS:
Pros - Attractive for display and decoration.
Typically more space than tubs, especially height.
Not always a good thing, depending on the BP.
Easy to clean/wipe down.
Not as easy as a tub.
Hold and spread heat well once insulated.
Keeping humidity can correct can be more fun than a three ring circus, however!
Smaller sizes not too expensive/easily found at sales and online.
Cons - Heavy!
Unable to be stacked without special adjustments
Easily breakable if dropped.
Take tweaking to get things stable
TUBS:
Pros - Lightweight.
Can be cheap $$.
Fairly easy to clean and disinfect.
Cons - Too unstable! Temps and humidity keep shifting.
I've never had this problem.
Ugly! Even the clear ones.
Ever ask the snake what he thinks?
Usually too short for explore-loving snakes.
Widely known to populate the BP world!
Not as much overall space (floor is smaller than upper dimensions)
That's why they sell them in a wide variety of sizes