I think a better comparison would be antidepressants. A common class of antideps are called SSRI -- selective serotonin re-uptake inhibitors. They have a similar mechanism to MDMA -- block the re-absorption of serotonin by neurons, so more serotonin is available for neurochemical processing.
Stimulants mainly act on the dopamine system, although MDMA might act on both systems: dopamine and serotonine.
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MDMA is also quite toxic in long-term usage.