fun world gen or as the .jar is called FWG it has a few other options and the author has a few different mods that also change the world gen for example realistic world gen. I highly recommend to check it out.
edit before I forget if you go for floating world gen you can't get the ores that spawn like diamonds as your world doesn't go low enough. I choose to go with ex nihilo + ex astris to get my ores but another solution could have been to change the ore gen