I enjoyed all 4 games as well. Sadly played the first two games back with the horrid GFW Live shiznit. Later Steam gave me the GotY editions for free, the ones without the GFWL crap in it. Didn't expect WB to be on board with something like that. Nice though, since those who had the GFWL versions didn't get shafted after the service's discontinuation. Arkham City wore me out by the end of it, so I was already kinda fatigued, but I decided to give Origins a shot. I don't recall the gap in time between when I played AC and when I played AO, but I probably needed some time after AC (and no, I didn't even try to get 100% completion, as I had done with Arkham Asylum). I used a friend's copy to play AO, just intending to try it out, but I kept with it, eventually finished it, and yeah, weakest of the three, but still enjoyable.
It took me a looooong time to get around to Arkham Knight. Actually just did it earlier this year. PC port was trash upon release, and then the game kinda fell off my radar, and I forgot about it over the years. I don't even remember what reminded me about it, or got me wanting to finally check it out. I got that whole Batman collection that EGS gave out for free, but ironically I used a friend's Steam copy to play it. Ended up really enjoying that game too. I think waiting so long to get back to the series actually made me more willing to dive back in. Plus the passage of time meant newer beefier hardware could apply brute-force to overpower the PC port's performance failings.
Very surprised that WB decided to release some of their stuff on a DRM-free store. Hhhmmm between this and Sony releasing HZD on GOG, I hope this is the beginning of a trend.