Didn't spend much time in the NFT Space, but OpenSea was always a good point of reference
I've been a regular user of OpenSea for quite some time now, and I must say, they are continuously dedicated to enhancing their product. They consistently strive to improve the user experience (UX) and communication aspects of their platform. It's impressive to witness their commitment to making OpenSea even better. I'm genuinely excited to see the progress they will make in the upcoming period.
I've used OpenSea for almost all of my NFT purchases. Overall my experience has been positive. However, the User Interface has been confusing when delivering error messages (such as just saying "transaction failed" with no clear indication as to why that happened) or an offer expires but still remains on my offers page. I believe OpenSea allows for people to purchase NFTs easily (even using Fiat currency) and provides overall good user experience.
OpenSea's search engine and NFT analytics makes using the platform easy and painless. From linking my MetaMask to buying NFTs, everything was a one-click and done process. My only complaint is that stolen NFTs are still allowed to be sold on OpenSea and while OpenSea has done their best to flag these products, it's not enough and I believe they should ban these users from the platform, rather than letting them re-list. While the stolen NFTs can be confusing to a first time user, I do appreciate the blue check mark verification on projects. It makes me feel safe knowing that OpenSea has vetted a project to ensure that I am buying the official NFT project and not a derivative of the original.
Good marketplace which I think handles multi-chain relatively well - the studio stuff they've recently recently is really cool as it gives NFT projects the opportunity to really showcase their brand a lot more.