Both my breast surgeon and oncologist told me that Letrozole was the AI that supressed the most oestrogen. I was curious so did some research. It wasn't hard to find articles referencing this. Attached two links below. Both my doctors also said the differences were considered very small.
There are many factors influencing what drugs we are prescribed. Age, how developed our cancer was, weight, tolerance and most of all how oestrogen receptor positive our tumours were. Mine was highly ER+, so I am interested to persevere with Letrozole for as long as I can manage. What drugs we take is a matter for each individual to discuss with their doctor.
So let me rephrase, Letrozole is the best one for me.
https://www.futuremedicine.com/doi/full/10.2217/fon-2017-0228https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3068499/