3-FMC is a non-remarkable straight stimulant. It's my understanding that 4-FMC is a bit more recreational (probably because that 4-substituent gives it a touch of serotonergic activity).
Neither of them are anything worth calling home about.
Cface:
No, 4-FMC is not on the level of cocaine.
Crystal meth is the king of stimulants, with a ceiling in the stratosphere, a duration that forces you to redose to meet work obligations the next day, and is generally ridiculously potent. Cathinones get nastier in terms of peripheral sideffects faster if you binge, also. Meth is probably no worse (quite possibly more benign) with equivalent "intensity of use", but it lends itself to much heavier use.