It all depends on what you want to use it for.

Personally I prefer a short and light bow because I hunt at high elevations (11,000) feet and I am usually sitting very little at all so having a light and short bow is paramount for me.

If I were to shoot targets I would want to have a longer and a bit heavier bow Say 38+ inches.

If I did most of my hunting out of a treestand I would probably want one somewhere in the middle. Say around 35 - 38 inches.

Remeber that the heavier and longer the bow is the harder it is to induce torque to the bow.