As Markus said: if you get the MKS Gen-L, you don't need the RAMPS board, since the MKS Gen-L has everything that is on RAMPS built in (driver sockets for motors, ...etc.)
Regarding the power, you never run the driver or the motor at the max rated current.
Usually, you start at 40% of the motor (so 0.675A), and then test, tuning it up to say 70% of the 1.68A as a maximum.
You find where the sweet spot in that 40 to 70 range, that gives you fast slewing with no resonance/stalling.
You don't need the TMC5160 for those motors. The TMC2130 should be able to handle them, but make sure you have the heat sinks installed and monitor for excessive warming.