Our experience is with the Horiba models and the good old Myron L Agri-meters. The Horiba models are the B-213 twin ph and B-173 twin cond. They seem to give very accurate readings and are portable. The sensors seem to be just a little fragile and the cost is high. The Horiba is the most accurate we've used. The other EC meter we use is the Myron L AG-5. These are very durable and reliable but less accurate than the Horiba. We like the AG-5 because it is fast and easy and really needs very little calibration. You have to calibrate the Horiba every time you use them which means you need to get the calibration solution, distilled water, and ph calibrating buffer solution. You calibrate the AG-5 with the push of a button. The AG-5 is perfect for getting a quick EC anywhere in the greenhouse without having to haul around a kit. We do not have a Myron L AG6/ph but this model operates much the same as the AG-5 only it also gives ph. We used to use Myron L and went to the Horiba, found it too time-consuming and costly to repair and now we're back to "old reliable". I would recommend the Myron L models for quick, easy EC and PH readings and durability. If you are looking for excellent accuracy I would recommend the Horiba models.