What is your favorite OPK?

Erica • 31 yo. Mommy to baby girl - 20 mos old. TTC #2.

My husband and I have been TTC for 3 months now. Last month I used the cheapest strips at CVS, but was unsure about reading them. This month, I tried the ClearBlue Advanced Digital for hopefully less guess-work. However, this has been a bust because I have only gotten flashing face (High fertility) and no solid face (peak fertility with LH surge).

What is your favorite OPK that has been reliable?

I am 29 and this is our first time TTC.