The liquid slide comparators are better than the plastic ones but the only test this will affect is the pH test. The TF100 and Taylor K-2006 use the FAS-DPD chlorine test, which is a titration (drop count) test and not a colormetric one and it is much wider range (up to 50 ppm FC) than the DPD test, which will bleach out above 10 ppm. It is also more accurate than even the glass slide comparator so the TF100 or K-2006 are superior for the chlorine testing The other basic tests (TA, CH ) are titrations so they are the same in all the kits. the CYA test is a turbidity test so, once again, it will be the same in all the kits and does not use a comparator. The professional kit also includes acid and base demand (not that useful in most circumstances but if you really need them then get a K-2006 since it contains these tests) and iron and copper tests. If you need the accuracy then the glass slide comparators are better than plastic or paper ones for iron and copper but these two tests are available separately if you need them. My suggestion would be to get a TF00 (which includes an OTO test, useful at times) or, if you really need the acid and base demand tests get a Taylor K-2006. If you need iron and copper tests get the separate kit from Taylor that includes both those tests.