1. Dark Souls 3 - My first full Soulslike experience. I had briefly tried Demon Souls, Bloodborne, Lords of the Fallen, and Dark Souls before committing to Dark Souls 3 and this is the game that really established my love of the genre. To me it's the best combat system, the most appealing world artistically, the most replayed OST, and some great lore. I could see how some would identify it as fan service but for me it was my first dive into the universe so it all felt fresh and impactful.
2. Dark Souls (Remastered) - I bought the Prepare to Die edition on PC but due to its rough framerate and kinda dated feeling controls I could never really get into it. The difficulty put me off too as I was in a really busy time of my life and couldn't consistently give attention to a single game to get good enough to get through it. Then the Remaster came out and I saw that it fixed the framerate issues. Suddenly the controls felt a lot better too even if it didn't have the omnidirectional motion. In any case, I can see why this game is often regarded the peak of the series. It lays a lot of groundwork for the games to come in its world design and lore. Some of the bosses are kinda bullshit (I'm looking at you Capra Demon and Bed of Chaos) but all in all this game provides heaps of customization in build types and just has so much depth.
3. Bloodborne - 3 main things keep this from being #2 on my list. In a lot of ways it's objectively better than Dark Souls 1 to me. It has better combat, is far more consistent in its quality of areas and bosses, and is more visually striking in its art. But being tied to 30 fps with poor frame pacing, having a story and atmosphere I didn't gel as well with, and crushing me with Father Gascoigne early on in the game (seriously... I was stuck here for years) really sucked a lot of enjoyment out of it for me. Having said that, it's a stellar game and anyone used to console level IQ and performance should give it a shot.
4. Lords of the Fallen - This one is on the list by default because it's one that I played enough of to add to the list. But all in all it's a pretty meh experience. I bought it for $3 thinking it would be an easier Soulslike to ease me into the game type after my prior poor experiences with Bloodborne and Dark Souls Prepare to Die. But I played it enough (~7 hours) to realize I would love this style of combat if the enemies and environments were more varied and interesting. And they certainly were in Dark Souls 3 from all I had seen... so this was a testbed title for me and I have it to thank for making me confident in purchasing Dark Souls 3 and the IDLCs and I'm so glad t did.
Edit: Added more reasoning to my list
A bit of an update to my list. I've gone through Sekiro and am on the final boss. I'd put it at tied for #2. Dark Souls has way more replay-ability with different viable builds and I love the lore of that world just a bit more than Sekiro, but the second half of the game really hurt the experience for me. Sekiro has amazing gameplay and awesome boss fights. The music takes a bit of a back-seat vs From's other output as well and music to build atmosphere is a big part of any media consumption for me.
On any given day, I can be more in the mood to play one or the other so I can't really pick between them.