As Princess Pupule stated, it's really a matter or preference, comfort level, and risk aversion.
Getting euros upon arrival is the least expensive way to get local currency. But remember this: if you wait until arrival to get Euros, there is the inconvenience of having to find a machine, waiting to access it, the stress of hoping it works (they do occasionally malfunction and / or run out of currancy), and doing all that while somewhat jet lagged. Many think it's better to have some Euros in hand before arrival, and get two or three hundred Euros beforehand from their local bank. It will cost a little more, but the amount it cost to have money in hand when arriving is money well spent, and the cost relative to the overall cost of the trip is next to nothing.
No matter what you do, check with your bank and credit card companies to see if you need to put a travel alert on your account(s). They may see a foreign transaction, suspect fraud, and shut down access to your credit and ATM cards. Some banks require it, some don't, and some waiver back and forth.