im new to diveing wich tank is the best what are the different kinds and wich last the longest stuff like that and what ever else you want to ad
A tank is just a means to an end. I don't think you can see the "tank" separately from the configuration as a whole and the goal/type of dive you want to make.
Work your logic backwards from the question: "what do I want to do" and the right tank for that job will fit into the puzzle.
R..