MDAI and 2C-D was the closest for me.
Barring that, AMT by itself is like a candy flip (MDMA and LSD), methylone and mephedrone make a very MDMA like experience, and methylone itself (the crystal stuff not the cheap powder) can at times produce a short duration MDMA type high that's more horny than empathic and lacks almost all psychedelic activity but mix in some 4-HO-MET or another 4-sub and that problem is solved
I have not personally done so but I've heard that 5-MAPB and 6-APB is pretty much MDMA
Don't forget 5-MeO-MiPT. That stuff is the tryptamine answer to MDMA but it's stupid potent. 8mg on the come down of mephedrone resulted in a totally empathic, extremely sexual, and long lasting roll that came pretty damn close.
The problem is most of these things are gone. Hence the combinations suggested with 5-MAPB to make a roll... I believe a bit of 4-FA with a small bit of 4-HO-MET was said to be the closest? Lost track...
5-APB is still available and is said to be pretty close... At least I see fewer people making wild combos than with 5-MAPB.
Personally I was pissed when methylone went away... As far as a single drug (mind you I've never done an APB), it was the closest to MDMA... As it should be considering the only difference between them is an oxygen... Methylone was completely innocent without a single known death but was taken out as a cathinone like the mephedrone that killed so many...