I have hope for Worlds Adrift.

anemo

People keep clamoring for a new sandbox that has some impose-able PvPer in it, but that it isn't the point of the game. And this shows really good hope of getting there someday. Likely much later than promised though.

It has all the exploration that No Man's Sky promised. With player made islands (dev tweaked afterwards) that have some really interesting nooks and crannies, are unique, and an actual reason to explore for character advancement.

Has a great building mechanics that are outstanding and creates unique designs like Space Engineers(though more constrained, since Space Engineers has a 10,000 block limit). Quite simply put how well this is done in an actual MMO is amazing.

Has a unique leveling system that at first doesn't seem grindy, and has great potential after it's balanced. Basically everyone can use every piece of gear in the game, however the advancement comes in the form of learning blueprints to make the gear (from finding randomly, and from advancing a knowledge tree). You can also easily skip temporarily a bunch of power tiers by getting a more advanced character to craft with you (but it's lost on death in all likeliness, or if your ship crashes), which allows some great boosts for allies without breaking the game like it would in other MMOs. That being said there are A LOT of necessary blueprints that just aren't part of the knowledge tree, and the drops from chests are really really rare (Just saying that if I need to spend another 70 hours to get a part of core character advancement because of RNG I just won't bother with the game after its closed beta reset).

PvPer is there, brutally. it's probably a bit higher than normal full loot (no banks, no safe zones, ships(your home base) can be stolen/looted, and very little space that is kept on death). I would say that it probably would be a great start, but from developer talks/posts/FAQs it looks like they saw all the great ways that EVE reined in PvPer in 0.0space/lowsec and said screw it, all that stuff made griefing too hard. There will be no territory control, few ways to choke point your targets, core game mechanics make known islands much less useful so even your own guild/alliance members will drift distantly from you, no in game ways to even talk distantly to allies, no in game way to warn people who pirates are, and just about any other tool that gives people a way to socialize their way to safety just will never be there. Core mechanics in any form of a fight is fundamentally broken as well, the best weapon is the newbie pistol that takes 5 mins to make (compared to other weapons that require both pilot/gunner coordination, limited firing arcs, fractional damage compared to pistol, shorter range, a falling/arcing shot, a large number of resources, and a massive amount of knowledge investment).  88 hours in, have lost 2 ships to pirates, have had my ship silently looted a couple of times, and have actually died to a PvPer once. While killing off 3 that got close enough to attempt, and just being so much further advanced that I could just outpace 4 others (which means that while it's there it's also pretty easily avoidable). Also PvPer in general does nothing to actually advance your character in terms of knowledge/permanence (and devs have made it clear never will), but is great for acquiring materials.

Devs right now are keeping the beta worlds so much smaller than planned intentionally (a third to a fifth of it's planned release size, and with future planned low player densities) for stress testing (and with fewer servers than planned). And there are stress testing bugs. There is also a fundamentally broken graphical lag issue that will freeze your client every time the LOD of islands load for the first time, or a new island loads (this will cause your character to go flying away from your ship frequently, which might indicate that their servers aren't definitive enough but that at least that some of their net code is pretty broken even if it works under other conditions. Which hopefully doesn't indicate further underlying problems (graphical lag should never ever cause client server desync)).

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So in general if you've actually played space engineers multiplayer wish it worked, you have something that works many times better and is actually an MMO. But others will probably want to wait a good long while to see what the devs do to fix it in the future. Like wise the developers have proven that their game and tech work on fundamental levels (with baby spew), which goes quite a bit further than a lot of other MMO devs.

Dibdabs

I signed up for beta a few weeks ago, so I'm hoping to get in at some point.

One big drawback I can see looming is that you need your crew of players to fly the ship, and I can't see me recruiting any crew or retaining any if I did so, should they stop playing.  Who can even say everyone playing a crew member can even be online regularly at the same time as everyone else.