Top-level menus can be tricky and are a difficult decision for a plugin author.

I used to have a sub-menu under options-general (Settings), but found it incredibly difficult and counter-intuitive to create sub-sub pages, which would have been ideal.

To get around this, I created a top-level menu item for my plugin since it has, and will have several more, sub pages.

From a plugin author's standpoint, all we are given is a priority argument. We have no control of the sorting.

For the settings link, that is pretty easy to add to the plugins page, and I did so with one of my more recent versions. But again, adding this in as not as easy as one would hope.