Based on the evidence from images and models, Claim 1: Flowing water formed the channel on Mars is generally better supported by scientific consensus.
The presence of features such as valley networks, outflow channels, and sedimentary deposits suggests a history of liquid water flow. Studies of the Martian surface have identified signs of erosion that resemble what is seen on Earth where water has shaped landscapes. Additionally, the detection of minerals that typically form in the presence of water further supports the idea that flowing water played a significant role in channel formation.
While there is also evidence supporting the Flowing Lava Model, particularly in relation to certain volcanic features on Mars, the overall geological context and the extensive evidence suggesting past water activity leads to stronger support for the claim that flowing water is responsible for the channels observed on the planet.
Thus, the better-supported claim is that flowing water formed the channel on Mars.