KeeperRL's ASCII version is actually free and I think mostly/entirely up to date. If you're wondering about it as a purchase, you probably want to give that a whirl. S'on the game's actual website, somewhere or another. Vis a vis comparison, it's smaller focused than DF with less moving parts and (much) less focus on the little stories type thing that is DF's core, but it's also much less hands off with stuff like combat, and involves raiding and whatnot. It's definitely pretty dungeon keeper-y, with some nice added touches. Fairly enjoyable, imo.
Stardew is indeed very much not like DF -- it's a pretty direct spiritual descendent of the Harvest Moon (Well, more directly the Rune Factory stuff) series, not anything resembling DF's style of gameplay. About the only similarities are the story focus (though of a rather different nature from DF's procedural nature) and the fact that farming, fighting, and familymaking are involved. I'd personally recommend it, particularly if you can get it on the cheap, but if you're looking for something similar to DF it very much isn't it. It's also not like terraria pretty much at all, though. More the Rune Factory stuff, harvest moon with a dash of secret of mana (more like evermore, really, iirc) style ARPG combat (just sans multiplayer).
Both of 'em are either a lot more personal/give the player more direct control of a smaller number of critters than DF's primary mode, or more involved than its adventure mode. They both do lots different and offer stuff DF doesn't just by dint of being pretty much entirely different in regards to genre and design ethos, more than I'm willing to attempt to summarize with any more depth than the above, when I've only been awake like ten minutes.
Rimworld and prison architect I haven't played, heh. People seem to like 'em a fair bit, though, and PA's recently-ish started seeing some decent sales, if I'm not mistaken.
All that said, near as I can recall every one of the mentioned games have dedicated threads here in OG, and they've also got LPs floating around youtube with varying degrees of prolificness. If you're actually on the fence/tightly restricted about which of the four to get involved with, you probably want to watch some gameplay vids (maybe not with stardew, since it actually has non-procedural story bits and you can be spoiled if you care about that sort of thing, but the rest don't really have that issue) and skim over the threads in question a bit, see if what folks are talking about appeals to you.