For romantic it's all mlm; besides Ratio, I enjoy shipping Aven with Boothill and currently looking forward to what their ship with Sugilite has to offer! I'm actually open to pretty much any mlm ship with Aven, Gepard one is also very cute!
For platonic, I treasure his dynamic with Topaz and Jade a lot, need them sticking together! But also, ACHERON. One of my favorite relationships from Penacony is Aventurine's and Acheron's, they mean a lot to me, I don't expect to see more of them, but I'll be forever grateful if it ever happens.
I'm intrigued by his dynamic with Sunday, but nothing I've seen of them together has quite clicked with me, so I'll go with neither romantic nor platonic, but a secret third thing.