Since the X30 has the same sensor and lens as the X20, any differences will be down to its newer firmware algorithms, and lens profile adjustments.
But it should be easier to use and more accurate to compose.
It also has full remote and adjustments via a smart phone or tablet using wifi.
For instance if you stick it on a long monopod, high shots become easy and controllable.
The rx100 m3 has a larger sensor but smaller zoom range,It is far less adjustable you need to delve into the menu systems for manual type or advanced settings. it does not have wifi. It has a low pass filter on the sensor so looses some of its detail quality.
The rx100m3 is a very high grade consumer point and shoot.
The sony and the fuji are aimed at slightly different markets, as the X20/x30 controls handle more like a DSLR than a compact.