As Isaac said, let's not think in terms of "better", as if there can be only one strong online community for rich knowledge-sharing and Q&A. Mi Yodeya is an important community and we should not seek to diminish it. We should assume that many people will participate on both. If this site helps to increase learning about Judaism on the Internet, it will accomplish something important regardless of where else that is happening.
In this post I speak for myself only. In describing what I'd like to see here I will sometimes draw comparisons to Mi Yodeya. Those comparisons are not meant to be critical; they're just comparisons.
These are things I would like to see this site aspire to and grow in:
Broad inclusion: Chazal teach that there are seventy faces of torah. We are not all the same. Our backgrounds are not all the same. We sometimes disagree vehemently with each other. That's ok; so did our rabbis. Beit Shammai and Beit Hillel argued on everything, but they ate in each others' homes and their children married into each others' houses. If they can do it so can we. I want this to be a community where questions coming from diverse perspectives are welcome. I don't mean we should lower our standards; we have certain expectations of all questions and that remains the case. But somebody asking a question about a tradition that isn't my own does not diminish me; rather, it can teach me something, or at worst I skip past it. And because of our strong emphasis on sources and showing our work, it will become clear when a post does not measure up.
All things Judaism: This answer on the proposal for this community suggests a broader scope than Mi Yodeya and gained strong support during the proposal phase. This site is not only a halacha-and-tanakh site, critically important as those topics are. Let us also welcome questions about Jewish history, Jewish communities, and even prominent Jews. If they are not interesting they won't get votes and answers, and that will be signal. But if they are interesting, let us allow that knowledge to be shared here. Of course, questions must still be answerable (not opinion-based) and avoid issues of lashon hara.
Multi-modal learning: As I said in The Codidact Vision, Q&A is central to learning, but it is not the only path to sharing knowledge. I'd like to see our community support other content alongside our body of questions and answers, including a well-developed glossary or dictionary and divrei torah. We can use these other modes to broaden our shared knowledge both for us and for the whole Internet, and through other modes we can engage our contributors in different ways (which gets to my next point).
Strong community: Some of the regulars on Mi Yodeya have strong connections to each other, built through chat, meta, and interacting on Q&A (and probably through many, many comment threads). It's truly heartening to see the community rally around its individual members, such as when somebody recently asked after an absent member. And, of course, I'm touched by those who rallied around me. But sometimes people have had more trouble forming those bonds, whether the barriers are due to language, background and knowledge, or the tools themselves. I'd like this community to be a place where people can build strong connections and all who sincerely want to engage with Judaism and Jewish learning feel welcome. I think multi-modal sharing helps with this by removing a barrier to one kind of participation. Several times on Mi Yodeya we saw somebody come with an idea to share and grow frustrated when told it had to be shaped into Q&A. Here we can remove that barrier. It's my suspicion that somebody who comes to teach an idea or tell a d'var might then stay for the Q&A and become part of the community.
A welcoming and kind community: Newcomers (and sometimes even "oldcomers") stumble sometimes. Some questions really don't fit and can't be fixed; some answers do have profound problems; some ideas are beyond the pale. What happens next tells a lot about a community. I want ours to be a community where we offer the helping hand, greet the person with the friendly word, and walk in the path of darkhei shalom. This isn't about compromising quality, which I am not advocating; this is about how we engage with people. I want us to aim higher than "civil". And I know that this is especially challenging online (text-only) with a worldwide community and many different backgrounds, so I want us to also strive to be kind and gentle with each other and always presume good intent. I've learned a lot from my peers about how to disagree constructively online; none of us are born knowing this stuff. We should be welcoming and kind, and when we stumble in that we should be kind in how we correct it.
Jewish values: We should strive to uphold Jewish values and ethics in our participation here. This probably goes without saying (we all strive to uphold Jewish values in our lives in general), but it's worth saying anyway. There will be times when Jewish values place a higher demand on us than baseline social/Internet norms -- in matters of modesty, in how we talk about others, in how we handle disputes. We should model our best values here, through which we might be a small part of the or l'goyim.