I really like your articles and I think you deserve people trying to back up a little bit their comments. keep up with doing this terrific job :)

I am just vaguely familiar with decred, so I am not going to make any comment on that.

As for Tezos, it's fun, but even if I have no contact at all with him currently (and quite frankly no desire to make any contact either), I actually know quite well Arthur Breitman. He was a fellow student at university. We graduated the same year :) I don't like his character, but I have to recognize that the guy is intellectually brilliant. That's why I was considering investing in the ICO back in 2007. Very glad I kept my eth at the time though, because boy was the launch of this blockchain as mess ! Even if they seem to have normalized things, I am very skeptical that Tezos is going to do anything meaningful and I am floored by the current valuation : to me, it seems that they came to late to the party implementing a second generation blockchain with no ecosystem around it, little perspective of being as powerful as newer blockchains (EOS, Stellar...) and with very little differentiation (the coding language is supposed to be better to audit smart contracts and making them airtight, yeah okay - and this onchain governance : seriously is any layman really going to use this feature ?)
As I wrote, IOTA is the "blockchain" (actually a DAG) that has been the target of the most insane FUD I have ever seen : in itself, I take it as a rather positive sign that some people (bitcoin whales ?) are shit scared that it could meet its promises (we are still far from that but the team is insane, so there is a solid chance that they can pull this off and I don't see Volkswagen implementing a hardware solution running on IOTA for its cars due in early 2019 if there was not a good chance that they could pull it off).
As for bitcoin, I agree with you that with second and third layers it could encompass many features of many altcoins. The only thing that bugs me is its POW... In a world concerned with energy consumption, is it really going to resist a better more ecofriendly alternative ?