I found the CNC Shield much easier to set up than Marlin once I understood that 95% of the configuration was done with the $ configuration commands, not through recompiling the firmware.
GRBL is my go to for all my CNC machines.
It’s easy to learn, print out a cheat sheet of $ commands and your good to go.
Source Rabbit is a good gcode sender, it has some built-in touch of commands.
Very user-friendly.