The HM / Stas smartspring hook is the simplest hook on the market, there are no moving parts to wear out and it locks itself on the nylon / perlon hangers with it's return spring action.

The hook itself holds 4kgs on the nylon / perlon hanger meaning that you can hang up to 8kgs using two of them on one picture.

For a majority of pictures this will be a great choice, easy to use and adjust by the millimeter.