Smiley OPK's .vs. CBE Monitor???

Well I have been using the CBE fertility monitor for a year and a half....I know that it isn't always accurate, because the cycle that I had a cyst the monitor said that I O on CD 14 but I didn't get a temperature shift until CD 29... So I figured that I would go buy some OPK's with the smileys cause I never do very well with the lines. I was on clomid CD 5-9 and started testing at CD 10... at CD 12 I got a smiley...and today CD 13 I got another one...but my monitor didn't have me at peak yet?? So I guess my question would be...which one of these would be more accurate?? Any info would be great! Thanks