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[tyuner4]

I find that most of the ICO projects accept ETH since the tokens are developed from the ETH platform.

I have also seen BTC and Neo. There are some projects which accept various coins and fiat. You have to check the payment methods with the project you are interested to invest in.

[culberth]

Most of them are use Etherum because it has smart contract and easy payment. I don't know another platform but I've seen that some ICO use Bitcoin too.

[bhabygrim]

Well of course Bitcoin,Ethereum and Bitcoin Cash would always be the coins that are used on investing in an ICO.
I also seen some who accepts Litecoin and Dashcoin but it depends on the ICO.

[SolomkA]

Depends on how much risky investor you are.
Those who do not want to over-risk invest in bitcoin and etherum.
Some invest in ICO or promising altcoins.