I am thankful that at 40 my fertility is lower, and being in a solid relationship where we would both welcome a child, we can track my cycle and use condoms as needed.
Why the rhythm method? Well...from about 16 to 30, I had four pregnancies. First time was with a condom and spermicide, second time was with a cervical cap and spermicide, third time was a matter of touching, fluid and pre-ejaculatory sperm, and the fourth time was while I was on the pill; had been for 3 years and took every one. I had an IUD after my daughter but felt it during sex. After a year and a half, it just bothered me mentally that it was there so I had it removed. My ex and I used the "pull-&-pray" method for another year and a half with no pregnancies. It was about 7 years before I got pregnant again and I miscarried. (Difficulty getting pregnant and miscarriages seem common after an IUD but I have no statistical evidence to support that.)
Somewhere in there I also used Depo-Provera, the shots, for a few years. I did NOT get pregnant (a plus) but did stop having my period altogether, my libido went down, my fountain became dry, dry, dry and my mind got low, low, low (all negatives).
All in all, I don't think there is any great contraceptive for me.