Which is better OpenSea or Rarible?

I'm curious to understand the nuances between OpenSea and Rarible in the world of non-fungible tokens (NFTs). Could you elaborate on which platform offers a more robust marketplace, in terms of user interface, transaction fees, security measures, and the variety of digital assets available? Additionally, how do they differ in terms of community engagement and support for emerging artists? Finally, I'd like to know if there are any specific features or advantages that one platform holds over the other, making it a preferred choice for NFT enthusiasts and collectors.