I personally think it is preference, space and money combined. I have snakes both in tanks and in a rack. I like the rack much more as most of my snakes are now in one small area of my home and i don't have a bunch of tubs or tanks everywhere (which my fiance hates). It also is cheaper than purchasing 16 more tanks along with full accessories. I now can get a new snake and (after quarantine) house him for around $6. That is purchasing a tub and water bowl. My rack cost me around $300 to build vs around $200 (very basic starter setup) x 16 = $3200 for tanks! I honestly couldn't afford to house my new additions last year in anything else. So for me Racks all the way even though there is nothing wrong with tanks in my opinion .