Which denominations believe that John 19 indicates that the crucifixion had the date of Nisan 14? According to Wikipedia:


  The modern Jewish Passover and Feast of Unleavened Bread is seven days, starting with the sunset at the beginning of Nisan 15. 


and


  According to some interpretations, the Gospel of John (e.g., 19:14, 19:31, 19:42) implies that Nisan 14 was the day that Jesus was crucified in Jerusalem.


The article mentions that this was the first Easter controversy which petered out around the 4th century and that "Jehovah's Witnesses continue to celebrate the memorial of Christ's death on Nisan 14."

Recently, an answer on Biblical Hermeneutics asserted that Jesus was crucified on Nisan 14.  This indicates the interpretation is still supported in some modern traditions.  

Are there any denominations that interpret John 19 as placing the crucifixion on Nisan 14?  Do the Jehovah's Witnesses base their memorial on John 19?
All denominations, as far as I'm aware, agree that John 19 places the crucifixion on Nisan 14. John 19:14 is clear that this was "the day of Preparation for the Passover," that is, the day the sacrificial lambs were slain before the Passover feast officially began (see Exodus 12:5-6). Since Passover begins on Nisan 15, Preparation Day is the 14th.

The Quartodecimian controversy was whether Christians should celebrate essentially a "Christian Passover" on the 14th every year, or whether they should celebrate the resurrection day, the first day of the new week following the Passover.

The practice of celebrating Easter Sunday was soon adopted by the majority of Christians, though some churches continued the Quartodecimian practice for centuries.

Today many churches celebrate a Passover or Seder meal on Thursday evening before Good Friday, but as far as I'm aware only the Jehovah's Witnesses celebrate as the Quartodecimians did, with a meal on the 14th and no special celebration on the following Sunday.