Heroin feels warm and pretty good in general, you can look into the distance and focus on nothing. Everything seems brighter due to pupil constriction and you may get extremely drowsy.
MDMA as you know is a stimulant, you feel really really good and sensations can produce that orgasmic feeling throughout your body. With the openness and talkativeness, not to mention the eye wiggles MDMA just has more to offer me.