You can see a long running thread for Space Engineers right here and you'll notice 99% of the posts are about multiplayer these days. Again, not really a negative crit of Space Engineers as what it focuses on, it does well. Star Made and From the Depth have the content I want in spades. It's just that having a bunch of interesting blocks isn't enough for me and it the problem I have with 90% of these games. From the beginning you could tell the devs were primarily interested in two things: 1 - the multiplayer experience 2 - adding new and interesting blocks.
I may change my mind one day about Space Engineers as the devs add tiny titbits of SP content now and again but, I don't think that has ever been their goal. I've thoroughly enjoyed both but, Star Made is the title I keep coming back to. Besides the stock graphics, it is also seriously lacking in any kind of real sounds/music which doesn't help on the immersive side of things (I always play some of my music in the background). You can fight for control of sectors of space, form alliances, affect the economy, build your own massive fleets which can be AI controlled, build space stations and of course multiplayer support.
On the other hand you have a massive galaxy to play in with various factions and a living, breathing economy along with persistent fleets (recent update). Planets look a lot more impressive than they used to but, they still can't hold a candle to Space Engineers visual glory. Star Made is not gorgeous to look at (very minecrafty, though you do have all the usual building block shapes these kind of games come with these days), and has very little in the way of physics. For what I mean by the long run, see my description of Star Made below. On the downside you need a fairly beefy rig to witness it in all its glory and is lacking in content to keep you playing in the long run (unless you only do MP, of course). Space Engineers is gorgeous to look at, has some sort of physics engine going for it and the planets are a marvel to behold.
There are different fleet types like attack, defend, mining, scavenging and more that can be configured to contain weighted amount of ship classes. This includes patrolling ships that will respond to any attack, mining, and other events. There are more, some with lots of praise from what I hear (such as Interstellar Rift) but, I'd rather speak from personal experience. System fleets will include everything within an owned system of an NPC faction. The two that spring to mind are Starmade and Space Engineers.