All projects make unrealistic claims about TPS, security and best decentralisation consensus but on practical purposes
1> which is the fastest, most secured and decentralised blockchain already working ( i.e mainnet already running)
2> which is the most fastest, most secured and decentralised blockchain whose mainnet will be releasing in 2019 and how they compare to other competitors
3> which is the most promising upcoming project in the space which has solid team and don't claim unrealistic expectations
4> what is theoritacal maximum tps , best consensus and crypto security can be achieved according to technology available today and within next 4-5 years
Expecting answers from researchers , enthusiast , nakamoto son and all those who like to scratch there heads.
1) Presently most fastest blockchain infrastructure project is EOS with 3000TPS on mainnet and have surpassed number dapss transaction as compare to ETH.
2.A) Quarkchain is currently achieved 10000TPS and the mainnet will be launch before or on 31 March 2019
2.B) Zilliqa also achieved successfully 2828 TPS on testnet and have huge plans and funds in store make their blockchain project successful and adoptive in 2019 year. The mainnet launch is scheduled before or on 31st January 2019.
https://www.google.com/amp/s/itsblockchain.com/top-3-highly-scalable-blockchain-projects/amp/3) The most promising project is seele which is bringing blockchain 4.0 and targeting to achieve 100k TPS. They have very knowledgeable team and actively updates their community through social media.
https://bitcointalk.org/index.php?topic=2820292.new#new4) With the current technology every aspirant project is trying to overpass transaction speed of VISA which is about 22000 to 24000 TPS. There is huge research going on by several project like Quarkchain, seele, hashgraph, yogdrash etc only time well say who will succeed.