Kraken: Security, Staking, and Market Variety
It's not just because Kraken has lower trading fees than Coinbase, Kraken is a superior exchange in several ways.
Safety
Kraken is considered unmatched in terms of security. Kraken has never been hacked. I also appreciate that Kraken requires users to use 2FA (Authenticator app, not SMS). Coinbase is "user-friendly" which is another way of saying that they oversimplify everything in order to overcharge their customers.
Staking (Earning Interest)
My favorite Kraken feature is its very flexible "staking" feature which allows users to earn interest on specific cryptocurrencies (Kraken's staking feature is more like lending; Either way, you end up earning interest) and unlike actual staking (delegating coins to an individual validator, etc.), there's no protracted unbonding process. Kraken users can unstake assets back to their account's available balance in a matter of minutes.
To put that in context, it takes hours (or days) for assets staked with OK Coin to become available once one chooses to unstake.
Market Variety
Kraken has 549 markets while Coinbase only has 509. Might sound like a minor difference but those extra markets are some of the best.
Bottom Line
Save for Coinbase's "Learn to Earn" feature, Kraken is superior to Coinbase in every way imaginable.
The American branch of Binance, Binance.US, has the lowest trading fee and of the four centralized exchanges I use, it is the only exchange which sells BNB (probably my favorite coin) and supports the brilliant Binance Smart Chain (definitely my favorite blockchain).