Clear blue digital OPK?

Hi ladies! I have being using the advance clear blue opk for 5 unsuccessful months. I just wanted to ask if you girls prefer the advance clear blue opk or the regular one ( that only gives you two fertile days).? Any advise? Gunce do you have any opinion about it?                                       I had a peak w the advance one and i used wondfo just to confirm ( with the same urine sample) and the line was not dark enough! I was very confused! Thanks for all your help