I've got two of the four.
Wasteland 2: I liked it and it deserved more of my time, but it just wasn't as attention grabbing or immersive as Fallout, and some of the battles started to have a tendency to add more quantity versus quality enemies, making it a bit of a grinder in some areas. Overall, I'd give it a 3.5 of 5. I think I expected a bit more from the engine/visuals as well, but they nailed the look and the writing, it just needed MORE, I guess.
Shadowrun Returns/Dragonfall: I liked the first with some reservations and liked the second more. I realize that Harebrained is still a young and relatively inexperienced company, but it definitely showed with the vanilla version. It lacked content, but I enjoyed the content that was there. What I really wanted it a more open world approach to the cities, less linear mission choices, ability to do more one-off side missions for cash and experience, and the original iteration lacked all of it. The characters, however, I liked.
Dragonfall: They took notes, I think and took player feedback seriously, as this included more of everything that I wanted from the core package. While it still didn't take it QUITE to the level of what I'd consider a "perfect" Shadowrun game in my head, there was a lot more to do, more one-offs, more characters to meet, more stories, a longer main campaign, a city to mess around in, the ability to derp around on the cyberweb and a few other decent additions that felt better designed than the original. Where it fell short, imo, is putting out locations that you're never able to revisit, like a massive nightclub, only being able to land outside an arcade location and a few others that could have made excellent recurring mission hubs as well as a place to introduce more new characters. I'd give Returns a 3, and Dragonfall a 3.5.
I have not played D:OS or POE. (I'm more of a post-apoc/sci-fi/cyberpunk guy anyway, so W2/Shadowrun were higher on my radar to begin with.)