Ha! Interesting stuff really. It's like someone saying being bitten by a lion and tiger, you choose one-yet you're sure that on both occasions you're gonna die:)

However my be a lion is weaker:) well I don't know-certainly someone can fight it and win!

NOW MY OPINION IF THERE WAS NOWHERE ELSE TO LIVE:

CAVE: Too dark, Too much subject to erosion, denudation and weathering and rocky stuff of that kind.... Earthquakes etc

TREE: Wind, Coldness, small stuff of that kind.

MY CHOICE:
Tree!

Reason:
- Life (Enough Breathing space)
- Less risk to Earth quakes as it doesn't resist but instead moves with it.
- :) Fruits! If they are not in that particular tree, they can be easily viewed in other trees.

WELL, EXISTENCE OF ADVANTAGES MEANS DISAVANTAGES MUST EXIST TOO.
HOWEVER, WEIGHING THEM MAKES A TREE BETTER.

Blessings to you as you shift your bed to a tree:)