What is the least popular sonnet by Shakespeare?

It is difficult to determine definitively which of Shakespeare's sonnets is the least popular. Different readers and scholars may have varying preferences, and popularity can be subjective. However, some sonnets that have been less frequently anthologized or studied include:

1. Sonnet 66 ("Tired with all these, for restful death I cry")

2. Sonnet 73 ("That time of year thou mayst in me behold")

3. Sonnet 89 ("Say that thou didst forsake me for some fault")

4. Sonnet 120 ("That you were once unkind befriends me now")

5. Sonnet 138 ("When my love swears that she is made of truth")

These sonnets may be considered less popular due to their complex language, lack of a clear narrative, or absence of well-known themes or imagery. However, it's important to note that popularity is a fluid concept, and over time, different sonnets may gain or lose prominence in the literary consciousness.