I like Guterman. My vintage machine doesn't hold much on the bobbin and I can get a lot more thread on a bobbin with G than DD. I have always liked DD, but my LQS said it has changed and is coming off the spool twisting now. I am still buying it and haven't noticed a problem with my other machine. I am interested in a poly from Bottom Line, but haven't ordered yet. I am the rare person who doesn't care for Connecting Threads cotton. It's very linty and it breaks easily when I have to remove any stitches.
Color does make a difference. I've never noticed anything with white, but black DD is weaker.