My take is on Ardor with its childchains and smart transactions build onto NXT proven technologies which is 3.5 years old.
https://www.ardorplatform.org/It only miss point 3 at the moment, it has all the others, but the devs (
https://www.jelurida.com) are working on this improvement (point 3) with childchain subnet.
NXT currently does 100tps, it should be note that Ardor will do more than NXT at release since it is an optimize version of NXT. Then now that Ardor has solved the scalability issue concerning the blockchain bloat (point 1), the next objective by the devs will be to push the tps to the higher as possible.
In the end, i'm very confident that the team behind Ardor and Nxt will contribute at lot to the blockchain space.
I invite you to take a look at this very underlooked project.
PS. Some fork of NXT by others did achieved a lot in term of tps (800 tps) in private environment setting by the Russia’s National Settlement Depository:
https://bitcoinmagazine.com/articles/russia-s-national-settlement-depository-successfully-tests-blockchain-based-e-voting-system-1464198071/Now imagine what Ardor will be able to do.