NEO is good for that (other than being a good smart contract platform). You can just buy NEO, move to your wallet and passively gain some GAS.
Currently the dividend is around 5/10% yearly
I see a lot of you have and intend to hold the NEO, so you know how to store NEO in the wallet to receive free GAS?
Download NEO Wallet (Neon Wallet0.1.2 Recommendation):
https://neo.org/downloadCalculate the amount of GAS that you can get per day corresponding to your NEO number:
https://neotogas.com/English instructions:
http://coinsutra.com.ridder.co/DWZ3wMSee also Best Wallet for NEO and GAS:
https://bitcoinvietnamnews.com/.../en-neo-nao-la-tot-nhat-cho...
Depending on the number of NEOs you have, the amount of GAS you receive is not much