I've used ce2's and now clearos for over a year and half. They are not for everyone. There is a small routine that I perform on every new one out of the box. I use the clearo x from gotvapes. I only use the reg size.
I pull all plugs. Sometimes it is easier to remove the middle plug after filling with juice so it is lubricated. You can cut the slits bigger, or like I do lift the wicks slightly and then just put the plug back on halfway or so. I leave a gap between the bottom of the slit of the plug and wick. It doesn't seem to leak much but this allows airflow for wicking. I leave just the fill ring in nothing else. Leaving the little fill holes open lets air get into the tank for wicking. That's all I do and I can't get good performance otherwise. also vaping with the carto pointed down slightly ensures juice is around the coil and solves any dry hit problems you may have.
I clean once or twice a week with a dry burn. Doing that I get very good value out of them. They last me longer than any atty or carto I've used. Just pull the tube, rinse under water, dab wick with paper towel, dry burn until white, I don't clean or blow the soot off, put tube back on, and now it's back to vaping. Once you get them working it isn't hard to get the same great performace every time. You have to be willing to play with em a little.