Personally I wouldn't make this comparison between XMR and STEEM as one is a privacy coin and the other is a blockchain-based social media platform. I think Steem(it) is unique in certain ways, whereas Monero is mainly known as the most popular anonymous cryptocurrency. Long-term I think Zcash (that you previously mentioned) as well as smaller projects such as ZenCash and DeepOnion have more promising advancements in transaction privacy than XMR.