What's the best place to put CSS changes, and why?

I've started modifying Montezuma for my site. Following best practices for a 'normal' theme used to involve making a child theme, and then doing CSS changes in a new Style.css there

Now I see an Edit CSS option in the Wordpress sidebar, and that's where I've put all my CSS mods, and everything works.

But I've noticed most threads here talk about making changes to the individual CSS files through the Montezuma options, and in one 'newbie' thread JerryC talked about using the 'Lazyest Stylesheet Plugin'..

Assuming they all work - are there real benefits or drawbacks to any of these methods - or is it just down to personal preference?

I know I like to keep all my changes (and mistakes!) in one place.....