I think Harley is the life of the party
I don't believe the people writing her are as good as her potential is and
so for good or worse, her fun personality is strong enough to over come
the less than stellar plots and stories she has been showcased in for the
last few years.
Harley Quinn would be a constant staple in my collection if the writing was
better (for me), as it is, I will follow her next series and when the time
comes to cut back on titles, she (unless better writing comes along) will
be the first to go. (and I will get my thrills in Suicide Squad