Which "Kind of Blue". I'm so confused

The oldest release and/or the cheapest.

I am probably in the minority here by saying that I think remastered is an excuse to get you to spend money unnecessarily. Buy the new and improved version, bla bla bla...

While I cannot speak for that particular recording; some remasters make them sound better in the car and/or on portable equipment. On good equipment they sound worse. Again, I may be in the minority opinion, but it is what I hear.

There are some genuinely great audiophile remasters that are better, but unless you are really hardcore, they may not be worth the premium price.

If you have a SACD player, go for the hybrid multi channel SACD. It has the three original mono tracks corrected for the problem that was in all the original vinyl and red book cds. It does not get any better for Blue then the multi channel SACD, I have all the issues: vinyl, reel to reel, Cd and SACD and nothing beats the SACD multi.

The sessions were recorded at the wrong speed (too fast) and the problem was not identified and corrected until they found the safety copy of the master tape in the 1990's. The 1997 Columbia reissue features the corrected speed, as do the other reissues after that date. There have been many LP reissues, some of which feature versions of the album at both speeds.

In short, pick up something post-1997.

That is an interesting dilemma. This is one of the most famous jazz recordings ever. The recording at the wrong speed is the one that made it famous. If it ain't broke don't fix it.

By fixing it they have basically slightly changed the tempi and the pitch. But people loved it the way it was.

If the "error" was never discovered, who would have really cared? It would be different if the recording originally bombed before they fixed it.