If we are talking about Ethereum tokens - as mentioned the easiest way to enter the market for token is EtherDelta. But also you can make your token on Waves platform and get to Waves DEX. And if you have coin on its own chain, you can list it on new exchanges such as KuCoin and etc easily
Bitrex is exchange where first you find the most of tokens added to there for the trading. Next to this polenix, ether delta and binance are follows for the adding most of tokens in them.
You may check the coinmarketcap.com site there you will find the coin want to trade and where it is been listed so it is easy find the perfect trading site.