Regardless if you have a heavy, solid wood door or a light metal door, the garage door springs do most of the work of opening the door. My door is double wide, heavy wood, has weak springs, and the 1/2 hp chain opener wore out after only 8 years. (yeah, it did OK)

So, first determine if your garage door springs are sufficient. A very rough rule of thumb is you can open the door half way and the springs will hold it. (Yes, you disconnect the opener when you are testing this.)

If the door flies up or crashes down, you may be able to adjust the springs. They are powerful but I have done it slowly, carefully, and safely. DIY instructions at the professional site below.

After the springs are set reasonably (not perfectly), any 1/2 hp will do fine.

Here is a link that might be useful: DDM garage doors