I own the InspectorEXP and Mazur 9000.
All the units you mention are very expensive for the average consumers.
I would stay away from the Mazur units. While I like the features on my Mazur 9000 and it does seem to test like my InspectorEXP, the Mazur unit is very bulky and I hate having to unscrew the rear cover to change the battery. Then the battery is in a spot that the user could easily damage the unit during a battery change.
Understand that the pancake tube in these units are not very durable. When I bought mine the pancake GM tube only carried a 90 day warranty while the rest of the unit carried a year warranty. This tells me that they know what part is the weakest link in the units durability. Please be sure to check out the warranty on the GM tube.
The best units I have found for realtime 24/7 outside monitoring have been the GQ Electronic GMC model geiger counters. Mine is the GMC-200 on an air purifier, used with a Raspberry Pi mini computer from NETC with their custom software.
Read about my station/unit here:
https://www.netc.com/bb/viewtopic.php?f=13&t=203For rain samples and limited food testing, I believe any pancake GM geiger counter is a must have. Try the Inspector USB, I hear good things about it, but I suggest you also get a GMC unit and install outside on an air purifier. I promise you that if done correctly, you will likely not be disappointed.