Dear googlegoss, for a start, none of them are as accurate as we like to believe. What we can expect of them, though, is that they're reasonably consistent, and the better ones are. In my experience the SD Codefree is okay at that. I recommend you pick one to use, then when and if you run out of strips, switch to the other. Don't switch between them. That way madness lies.
I used to test between all three of my meters on the same blood drop, but quickly realised it wasn't getting me anywhere realistic.
Good luck sorting it out.
Oh, and preferring the lower reading one sounds good advice.