Test strips vs liquid.

I am wondering about the accuracy of the two. Many of the folks here say the test stips are highly inaccurate. For a long time I used liquid test kits. A few weeks ago I got some test strips(jungle quick dip) since they were out of the liqud stuff. I noticed a very high nitrate reading(40ppm) the first few times using the strips and upped my water changes to biweekly. Now that I have the liquid test kit again, it is almost not getting any reading at all, between 0 and 5 ppm on the color scale. I did add a few plants recently, but the test strips are still reading arround 10-15ppm at the same time the liquid reads 0-5. What gives? Are the strips reading high or the liqud low? I think I would rather go with the strips at this point, even if they are reading high, I will be doing changes before nitrates even reach 20 ppm. Any thoughts?

Thanks for the tip, I'll try it out. But what was so bad about the strips? Was it the inaccuracy or were they just hard to read?