...a friend noted that this year, the 25th of March falls on the Fifth Sunday in Lent. Which has priority?
I'd draw attention to the rubric found on page 960 of Lutheran Service Book: Altar Book:
It is appropriate to observe this feast day in all its fullness during Lent. However, according to historical precedent, when the Annunciation falls during Holy Week or on Easter Day (or also on the Fifth Sunday in Lent in the one-year series), it should not be observed at those times but may be transferred to a weekday following the Second Sunday of Easter.
Thus, acceding to our rite, it would be appropriate for those of you who follow the Three-Year lectionary to observe the Feast of the Annunciation on March 25 and simply omit the fifth Sunday in Lent. However, since those parishes that follow the One-Year lectionary enter into Passion-tide on the fifth Sunday in Lent, it is NOT appropriate for Annunciation to replace the observance of Judica. Thus, just as there is a difference between the lectionaries on the observance of Transfiguration, so there is also a difference this year on the priority of Annunciation. Three-year folks may (and really ought*) to celebrate it; one year folks will have to wait till after Judica to celebrate it.
*See the footnote on p. xi of Lutheran Service Book:
The observances listed in boldface are principal feasts of Christ and are normally observed when they occur on a Sunday.