Suggest N-channel to sink current to ground. They seem to be more efficien than trying to source that same current from a high voltage source.
An N-channel MOSFET will go between your load and ground -- on the "low-side". The gate voltage required to control it is a relatively small voltage near ground (eg: 5V) even if the voltage across your load is 30V or 60V or something. "Logic level" means that it is feasible to use 5V to control the gate.
Want Low Rds,
RdsON is the resistance from drain to source (across the current carrying junction) when the MOSFET is fully "on". This is typically in the few dozen to few hundred milliohm range -- ie: way under one ohm.
low input capacitance for low power loss in the device, and fast switching times.
The gate of a MOSFET acts like a little capacitor that has to be charged up to get the MOSFET to switch on and discharged to make it go off. The larger that capacitance is, the longer it takes to go from on-->off or off-->on.
When the MOSFET is partially on, the resistance from drain to source is high and the part will see a voltage drop and will dissipate heat. A part that can carry 10A fully on, might have trouble with 200mA when partially on. You want to keep the amount of time the MOSFET is partially on to a bare minimum when you're switching current.
Also search for MOSFET driver to turn that input capacitance on/off fast.
Since your puny Arduino logic level output only sources and sinks a dozen or so mA, you may want to employ a driver circuit to supply the larger current needed to charge up a large MOSFET's gate as quickly as you need, to get the on-->off and off-->on transitions very very short.