Just found Cryptonite (XCN). The coin seems to follow an unique approach with a "mini-blockchain" and should be an original scalability solution. The concept is a little bit similar to Ardor, but it was conceived already in 2013 and started in 2014 ...
It's on Rank 482 (!) on Coinmarketcap ... It seems it had a bubble in mid-2017 that has brutally deflated. I look if I can investigate the reasons ...
Waves has an amazzing project in hands and a lot potencial to replace eth or became a huge rival when we talking about ICO with the huge difference you can benefict from waves tokens, since the fees will return to you in the end. I do believe raiblocks, XRB is unique as well, instant transactions and no fees, some say its the competitor of Iota, the coin has been made from the scratch and has a nice and active team working into it.
For a list of supposedly unique coins it's a bit same-ey. Too few details on the technical side to be meaningful - Bitcoin's scripting language is quite capable of effecting smart contracts - for the same arbitrary definitions of smart and contract that everyone else seems to be happily taking for granted.
Unique? Try Datacoin - 128K of data stored on the blockchain per tx, Slimcoin - unique tripartite minting (by proof-of-burn, proof-of-stake and proof-of-work), Gridcoin - BOINC client, Gapcoin - prime gap search, Navcoin - unique anon system, and those are just off the top of my head. You might need to break down the technical aspects into categories and go for a top five in each. Top tip: ls -l ./src/qt/forms usually gives a clue to GUI extensions which may be offering special unique features and github is searchable.
(btw, every blockchain observing the bitcoin protocol is a directed acyclic graph)
Cheers
Graham
It is on purpose that the technical details are limited. Agree on Bitcoin scripting language[non-turing complete], but thats not on the top feature of bitcoin. Unique in terms of code written from scratch, instead of clone\and add few extra features on top of clone.