I've been to Maker's Mark, Jim Beam, Jack Daniels, Wild Turkey, Heaven Hill, and Four Roses (distillery not warehouse). Maker's was definitely the prettiest one to walk around and not to mention they give you delicious Maker's Mark coffee to enjoy while you wait for your tour. Jim Beam was the most interactive where you literally get to taste the fermenting mash, the white right off the still, and bourbon straight out of the barrel.
I will say the nice thing is if you shoot for going to Bardstown you can knock out the most distilleries in a single visit. Heaven Hill, 1792, Lux Row, Willet, Jim Beam, and Four Roses (warehouse not distillery though) are all within 20 minutes of the city, 1792 and Heaven Hill are right in it. Not to mention Bardstown itself is a beautiful place to visit. Across the street from the Jim Beam distillery is the Bernheim forest which is amazing to visit as well. Also IIRC the Jim Beam distillery is the only place you can pick up Old Bathtube BIB so keep that in mind. Maker's and Jim Beam both let you "make" your own bottle.
Four Roses distillery and Wild Turkey are both in Lawrenceburg and I was definitely a huge fan of the Wild Turkey tour, easily in my top 3. The Four Roses distillery due to the nature of having the warehouse at a separate location does kind of limit the experience, but the place itself has very interesting Spanish architecture.
If you aren't going to be going for a few months Heaven Hill is unveiling their new tour center sometime next year.