Fun fact time because I'm that guy.

Coke and meth are similar in that they both activate stimulate Dopamine (reward, motivation), Norepinephrine (arousal, alertness) Serotonin (mood, modulation).

However they do it in very different ways:

Cocaine blocks neurotransmitter reuptake from the outside, it stops the neurotransmitter from being released from the synapse causing the area to flood and the synapse to fire more strongly, but still tied to normal stimulation. I.e. your body still produces the transmitter based on normal stimuli, coke just keeps it there longer, stretching the existing signal.

Methamphetamine drives release from the inside. It pushes dopamine out and into the synapse, and has some reuptake inhibition that combines drive the synapses far harder than normal. In contrast to coke, it doesn't stretch existing signals from physiological stimuli, it makes signals regardless of what's going on.

In short, coke blocks the sink's drain. Meth turns on the tap and sorta plugs the drain. Slight advantage to meth here for ADHD. CNS depression that underlies it responds better to meth because the taps don't open enough to begin with. Normal psysiological stimuli isn't enough.

Both in theory could treat ADHD, but meth wins by a longshot because of the speed and stability of its pharmacokinetics. Coke is in and out too fast to give the user the therapeutic window of relief without causing spikes that trigger negatives like addiction or heart problems. Meth is slower and longer lasting. 20-60 mins for coke, ~4 hours for meth. Leveraging extended release (er) formulations pushes meths already superior action (turn on tap) into a daily therapeutic window, while coke is still just behaving like a party drug.

Source: Lots of personal research. ( ͡° ͜ʖ ͡°)