As far as I know, I don't think one is more accurate than the other. I think it's just a matter of convenience. With the test strip, you have to first pee into a cup and then dip the strip into it for a few seconds and lay it flat until the result is ready. The midstream is just how it sounds, try to hold it in your urine
stream for a few seconds. Personally, I buy the test strips from early-pregnancy-tests.com since they are cheaper and buy little plastic disposable bathroom cups to use with them. They have worked for me so far. Hope this helps. Good luck to you!