The EUR is the strongest. The USD is the weakest.
A snapshot of the strongest and weakest currencies at the end of the calendar year is showing the EUR is the strongest currency while the USD is the weakest.
The ECB kept rates unchanged in 2017 while the Fed hiked rates three times. The Fed is expected to raise rates three more times in 2018 while the ECB is expected to once again keep rates unchanged. Go figure.
In the runner up positions for 2017, were the GBP which was a distant 2nd to the EUR but recovered from the 2016 Brexit tumble. The RBNZ badgering that the currency was too high, worked in 2017 as it was lower vs all the major pairs with the exception of the USD.