Depends on why you like the 65g with bean animal better...
If you like the 65g DT better for some reason other than the overflow - shape of the tank, the way it fits the room, etc. - then go with it.
But if you're making the decision based on the overflows alone, then I would go with the 90g and just make sure the sump has a properly sized return chamber.
I say this because the 90 will obviously give you space for a wider variety of livestock. And, if the return chamber of your sump is sized so that the volume of water it holds during normal operation is less than the extra 'head space' of your display tank, it will be impossible for your DT to overflow and cause a flood if your drain pipe ever gets clogged (... making the 3rd/emergency drain of the bean animal completely unnecessary).