It depends on what colors your going for. I’m always a fan of neon green nepthea, and green star polyps (though keep the GSP isolated as it can take over). I also like the Colt Corals and maybe a corky finger gorgonian. I’d stick with soft corals for easiness. Green toadstools as well (especially the long polyp/weeping willow varieties). Many mushrooms are easy as well (and there’s nice varieties and colors depending (from basic greens and red to ones like OG Bounce, Sunkist bounce, etc) - some of these can be relatively invasive. I also like pulsing Xenia and Kenya trees (but both are also an invasive coral if not kept in check)