I use FF because it's free. I have pretty "regular" cycles and temp pattern so it works for me. But I have heard other ladies prefer tcoyf. YOu could also learn to chart and interpret your own cycles!

Just kidding!!!
I'd say if you aren't having trouble with FF, then stick with it. No need to spend anymore money!!!

I think FF is more accurate than not if you are charting temps, with CM and using opk's will also increase the accuracy!
Good Luck! PM me anytime you have any questions.