In this post, I'll be going through the two types of exchanges we have. The instant centralised and instant decentralised exchange types.

An instant centralised exchange is one that converts one cryptocurrency to another instantly, but is controlled by a central body. That's where the centralised part comes from. One of the best ones and the one I absolutely recommend is Changelly.

As you might have guessed, an instant decentralised exchange is everything an instant centralised one is, except they aren't controlled by any central body, and are usually based on a blockchain.

Their being based on a blockchain means that they can only convert between the cryptocurrency types on that blockchain.

An example is the DEX in the Trust wallet. It is based on the Ethereum blockchain, and can be used to convert from any ERC-20 token to Ethereum, and also from Ethereum to some ERC-20 tokens.

Now, what are the advantages that a centralised instant exchange has over a decentralised one?

• If something goes wrong, you have someone to call: I remember when I once DEXed my BAT to Ethereum because I urgently needed Ethereum. My BAT balance was deducted from my account, but my Ethereum didn't show up until 3 days later. The trust wallet apparently set my Gwei balance very low, so my transaction fee was very small, and no one wanted to process my transaction. It eventually went through, but for a casual user who has never heard of Gwei is, it might be a big deal. Centralised exchanges like Changelly actually take proper care of the customer to know their problem. I have also experienced a problem with Changelly when I forgot to add a memo to my XLM transaction. I contacted support and they fixed the issue for me in under 3 hours. With a decentralised exchange, I would have been stuck till today or until I learnt how to fish my transaction out of the blockchain.
• They have fixed fees: This is a very good thing, because the risk of the fee change is insured by them. I have once paid $5 and $0.01 to send the same amount of Ethereum on two different occasions. Exchanges like Changelly factor in the network fluctuations into the fee number, so you're always sure of how much you're paying.
• They can change from a wide range of cryptocurrencies: Since they aren't based off a particular blockchain, they can change from one blockchain based cryptocurrency to another entirely different blockchain based cryptocurrency. There's a whole ton of utility in that. It allows for very dynamic pairs, like from Golem to BTC, a pair you can't find on many exchanges.

Now, what are the obvious advantages that a decentralised instant exchange has over a centralised one?

• A decentralised exchange pushes the future of crypto: Crypto isn't supposed to be controlled by anyone. It's supposed to be free. These exchange types carry forward the whole objective of crypto in the first place: Removing control from a single body and sharing it among the masses.
• DEXes are much faster than Centralised exchanges: Since they are based off of the blockchain of the cryptocurrencies you wish to exchange, they are very fast in changing from one crypto type to another. I once changes 3000BAT to ETH in under 2 minutes! With Changelly, waiting time is usually 5-10 minutes.
• You contribute to the blockchain when you use a DEx: DExes are connected directly to the blockchain. So the fees you pay are to the miners on the blockchain. This promotes the growth of the blockchain as the cryptocurrency is nothing without its miners, and the miners are nothing without transaction fees, which you have just helped in paying.

So which one wins this fight given the points I've listed? Tell me in the comments.