15g isnt much of a difference, with either one your gonna only have room for about 2 oscars. i know the bigger tank might make it a bit easier to keep waterquality (marginally since 15g isnt much afterall) but really... how much cost difference is there??? do the scratches really bother you???? my 8' tank had turtles in it, its all scratched up, and accordingly, i got it cheap cheap, so its a fair trade for me. just depends on you i guess, i would consider costs, and just look and see which you would prefer. if they cost about the same, id get the newer tank, it should last longer without needing refurbished. peace of mind counts for alot when you think about the possibility of a couple hundred gallons of water on the livingroom floor.