Best BBT thermometer to use??

Emily • Mrs 3/21/15 Mama 3/31/16 Due with #2 May 2019
I just bought a CVS one and it sucks already. I'll have it in my mouth for about 10 minutes and it's STILL not done reading! It won't beep for anything and I'm following the directions promptly. Now looking at reviews on it, everyone pretty much agrees that it's horrible. 
So I'm looking for the most accurate, fast BBT thermometer that you love?? Please and thank you!