I need assistance on deciding between the flir one pro and the E5 or E6"
Answer: It depends on what you use it for and how often you want to use the thermal camera.
The FLIR One Pro is a great camera but only has a maximum one-hour battery life before it requires recharging. This is not a huge issue if you only want to use it briefly, as it will go into standby mode when not being used to conserve the battery life.
The FLIR E5-XT camera is a more professional style standalone camera. Technically, it has the same thermal resolution as the FLIR One Pro, but in reality we find the images and reports produced are a much higher grade. It also has a removable battery with a four-hour battery life.
The FLIR E6-XT camera has a little over double the resolution of the E5-XT camera, so will provide you with clearer images and is more suitable for certain types of building inspection.