Never used changenow.io and I have used the other two for a couple of trades but right now on I'm using binance for my daily trades. And though registrations are disabled, I can jump off to other exchanges like changelly. When I want to step on other exchange this is what I prefer.
about Changelly and verification is a good point.
No ID verification = less hassle.
ChangeNOW is fairly new. Never had a problem with them: no verification, no limits and 0.5% commission
I see that's why I'm not familiar with changenow and this is good for us who are looking for an exchange that has the lowest fees.
I haven't used the exchanges mentioned by you. Tried Changelly once, but their so called "miner's fees" is so much more than the actual miner fees of a particular coin. Never touched Shapeshift and Changenow.io.
Most of the exchanges now does have an "expensive" fee so try to keep on looking with other exchanges that will give us some good fees to cover when withdrawing.
I personally use blocktrades.us for almost instant exchanges. I found it easy to use, no verification or even signup and fee is also very less. Fees varies according to the network congestion. Most people use it for Steem/SBD to Litecoin/Bitcoin exchanges.
This is another unfamiliar exchange for me.