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.