your question is unclear, you need to explain more. a masternode is not something you could "market"! it is something like a full node that users decide to run on their own and help the network by processing transactions and getting paid for it.
all you can do is to encourage others to run the masternode of a certain coin by introducing to that coin and telling them about the benefits of that coin! good luck with that

Binance is a reliable option if you are looking for a centralized exchange, although they may not have the most listing pairs given the fact that they have quite stringent rules for what coins will be listed. But what are listed will be liquid markets.

If you are looking for a DEX, I think that your best bet is probably Idex at the moment. They have a relatively high volume for a decentralized exchange.

But really, you need to be more specific about what you want to trade. Try searching up your ERC20 token on cryptocompare, and then going through the listed exchanges. They have quite comprehensive reviews for each exchange also.

I think it's not alternatively, it is more important. When you try to sell the erc20 token on an exchange, can be going hard if there is a low trading volume. Of course, there it can be a restriction per exchange, depend on from which country they coming.
So, trading volume is a number-one parameter for exchange choice.

Probably Binance[1] if the tokens you're planning on trading is supported.

If you're planning on trading those tokens that are lesser known though, do some research on DEXs.

Alternatively, you can see which exchanges certain coins trade on by looking the up the token on Coinmarketcap[2], and clicking on the "Markets" tab. The exchanges will then be listed below:

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[1] https://binance.com/
[2] https://coinmarketcap.com/