I suggest going for option 1, using a button to toggle the sidebar.
Since toggling the sidebar on or off changes the layout of your site, it can be fairly annoying for the user, if it changes without their consent.
Imagine reading an article, when suddenly the layout changes and the text shifts, just because your mouse wandered to the hover area.
I've created a mockup of your site design using option 1. If you scroll a bit and then toggle the visibility of the sidebar (by pressing the button on the right), you'll notice the text shifts quite a bit.
Additionally, hover related actions are incredibly difficult to pull off on a touchscreen. By showing the sidebar on hover, you effectively restrict the user's ability to navigate through your site properly, using a smartphone or tablet.
About toggling the visibility of the sidebar:
If you were looking at the mockup on a large screen, you'll notice the text can be a bit painful to read due to the length of each line.
Since your design shows the content being delivered on multiple columns, as opposed to only a single one as in my mockup, you are probably aware of the fact that too much text on a single line can be uncomfortable to read.
What you could do, is design a single-column view for mobiles, with the sidebar collapsed and expandable through a button click, and increase the number of columns on bigger screens, with the sidebar always visible and non-collapsable.