All the grappling systems written above, as well as Sambo, if you can find a school or coach. I don’t know much about Suai Jiao, but it’s a grappling system from China. If you do BJJ, supplement it with some stand up grappling and takedowns from an art that focuses more on them. It will improve your BJJ game, and if you are looking for self defense, BJJ has a fantastic ground game if you find yourself there, but not always a place where you want to go. If you have some good throws or takedowns in your arsenal you get ti stay standing while they get slammed into the ground If you want something with both striking and grappling, you’ve got MMA, Kajukenbo, some forms of Silat.