While I mainly use a bunch of FabFilter and Universal Audio plugins for mixing, I wanted to see what was possible using only free plugins. I used a mix of free plugins that come standard in Reaper, some from Analog Obsession and a really cool bass overdrive plugin from Modern Music Solutions.
All of those are free and I think they yield great results. You should definitely check them out, especially the Analog Obsession plugins. They have some really, really cool stuff.