Liquid hydrogen has what Elon Musk calls the pain-in-the-ass factor. It requires much higher volume tank at much lower temperature, adding lots of mass to the rocket, and it's impossible to effectively seal. RP-1 kerosene has the inconvenience of requiring your planet to have been covered with life a hundred million years ago. So, methane is the liquid fuel of choice for future martians.
Methane, while less dense (thus requiring bigger tanks) has a higher specific energy than kerosene, and thus has a higher ISP (rocket efficiency). Methane is also less sooty and should have better cooling as its a "mild cryogenic" like liquid oxygen.
Basically, it's between LH2 (hydrogen: high ISP, very low density, very very cold) and RP-1 (kerosene: lower ISP, high density, room temp) and may be a good compromise.
And its derivable on Mars. Downside is there's very little flight heritage for a methane engine, so most of this is theoretical.
