Given that u r looking for brackets I assume its going to be permanently 'down' & not hinged. If this is the case, a more squared off at the sides eg less arch, is more practical. You have uniform area to step onto rather than a reducing area. Ok for you guys but guests can get it wrong. Below are a few pix to show how its normally done in NZ.
Like most things in life a bit longer is better, you want to be able t sit there & lean back without the fear of sliding into the water.