Oh God. That’s like asking what poison I would want to drink. Trees are fast, but like what happened with Rose, if I needed a root item everything else is gone. Stacks are useful, but the fact that the items were ejected like a Queue when it was a stack really urked me. So I’m going with Queue, just because it has a simple method: add stuff to the back of the line. And you either use the first item, or you don’t