And I think that BTX is just too similar to all other coins which are faster than BTC.

BTX is:

1. fast - a lot of other coins are fast
2. cheap transactions - a lot of coins are even with free transfers
3. secure - almost all offer this as a feature
4. decentralized
5. anonymous to some extent

So BTX now is without the claimed fork coins (already claimed) and the airdrop coins (already ended).
My question is - what is the unique trait of BTX which is good enough to
make BTX a payment leader?

If it works for you, you can compare it with LTC for example.