Which version of Marlin are you referring to? There seem to be more forks of Marlin than I can keep track of, and each one adds different features. The Android firmware used in smart phones has the same fragmentation problem. Someone added Z-probing for Delta printers that everyone agrees works better than Repetier's implementation, which is the latest feature causing a mass migration among the more serious printer developers.
My personal preference was Repetier due mostly to the innovative web config tool, but I do have a working Marlin build for by printer. I say that my preference *was* Repetier because I just bought an Azteeg X5, and the process of configuring Smoothieware is so simple that it makes the innovation of Repetier's web config tool combined with the whole Arduino flashing experience seem obsolete. Let me add a small disclaimer that I still don't have the X5 installed yet, so I can't comment on print quality or how it works yet.....