I would consider Daredevil to be the best of the Netflix shows, with probably the most consistent quality throughout.
Jessica Jones has an amazing first season that I'd consider on par with Daredevil's quality, but the following seasons felt like a big step down. (Season 2 in particular had a few things that
really annoyed me)
Luke Cage has a first season with a great first half, then a comparatively underwhelming second half. Season 2 is consistently pretty good in my opinion.
Iron Fist is definitely the weakest of the shows, though I still enjoyed it overall. The second season is a noticeable step up from the first.
I thought The Defenders was enjoyable overall, but the story had some weak elements and missed potential. The character interactions were by far the highlight.
The Punisher has a great first season, and a somewhat weaker second season that suffers from storytelling that, while enjoyable, was almost bafflingly disjointed in some areas.
If I were to rank the shows overall, it would probably be Daredevil>Luke Cage>The Punisher>Jessica Jones>The Defenders>Iron Fist.
By season, it would be DDS3>DDS1>JJS1>LCS2>DDS2>TPS1>LCS1>JJS3>TPS2>TD>IFS2>JJS2>IFS1
Overall, I'd still recommend watching each show in release order at least once, as I wouldn't consider any of them bad, even at their weakest. Maybe "meh" on occasion, but still enjoyable more often than not.
MASSIVE WARNING THOUGH!
Netflix might be taking down the shows on March 1st, so anyone still wanting to catch up on them should probably hurry! (unless they are willing to pay for whichever streaming service they are moved to, that is)