BBT, OPK, or CM

Sa
Hi, I'm trying to decide what would be the better choices in checking for ovulation. I'm 41 I've had 2 loses, I have pcos which is under control, have regular cycles 28-29 days. 
I wanted to know is basal thermometer, opk or cm is the best way to check and which brand of thermometer or opk is best to use? I'm presently in my 2 ww, my cycle is due for the 25th though I hope it doesn't show.
Any help you awesome ladies have is greatly Appreciated