Flourite is popular.
Treated carefully, it does not cause clouding. But you would do well to do a search on this board and some others to learn about planted tank enthusiasts' experiences and related advice.
My personal advice is to place it in a bucket, squeeze out an old filter over it, add a little water to cover, and let it dry out completely over several days. It can become a little smelly during this process. When completely dry, lay out on newspaper to make sure, place in your aquarium, plant and fill carefully with water.
Other people repeatedly wash Flourite to rid it of dust. It requires a lot of washing. By using the method I have detailed above, you will find that the small dust-sized particles bind to the main grains.
I also add some coarse silica sand to Flourite. Flourite by itself is a bit coarse, IMO. The sand makes it easier for plants such as Eleocharis, Marsilea etc to establish roots.