Just wanted to add my $0.02 worth here...
As someone who has smoked, insufflated, or ingested a decent range of the substituted and unsubstituted dimethyltryptamines, in various forms (DMT [smoked as freebase, ingested with Syrian Rue, and as part of an Amazonian ayahuasca brew], 5-MeO-DMT [smoked as freebase], and 5-OH-DMT [insufflated as a prepared yopo snuff]) I can only say that 5-MeO-DMT is truly powerful, exquisite, and sublime. Far and above more powerful and pristine than the experience of smoking DMT itself.
That said, probably nothing can ever compare with the experience I had on yopo, and it raised a whole host of questions for me as to what--and how--the experience of pure bufotenine might be, but that is probably best left for another discussion. Let's leave it at the fact that I have no longer any shred of a shadow of a doubt that that chemical is the primary--iand perhaps even the exclusive active agent--in an entheogen of the highest order.
However, in terms of the discussion at hand, I will wholeheartedly agree with MGS and others who've praised 5-MeO-DMT above all others. It is truly the most intensely, directly, overwhelmingly spiritual and revelatory psychedelic experience I know of that is available through partaking of a chemical catalyst. I'm not the only one of my community who feels this way, either. I've come to describe it as the distilled quintessence of the psychedelic experience.
Also, just wanted to second the reference to the reports Shulgin includes in TiHKAL. It's not that TiHKAL is, by any means, the end all and be all of experiential references (really, it's just a nice place to start for a quick overview), but a quick perusal of the reports included under both DMT and 5-MeO-DMT paints a stark contrast between the two. There is one report, in particular, included under 5-MeO-DMT that really captures some of what my experiences have included:
(with 15 mg, smoked) "At about 60 seconds after I smoked this free base, I beheld every thought that was going on everywhere in the universe and all possible realities while I was wracked out with this horrible ruthless love. It scared the hell out of me. When I could see again (15 minutes later) it was almost as if there was an echo of a thought in my head saying that I was given an extremely rare look at the true consciousness of it all. I've never been hit this hard since then. A definite ++++."
At any rate, suffice it to say that this material is among the most precious and powerful of all entheogens, a crown jewel as it were. It may have an equal or two among its peers, in some form or another, but none surpass it in my opinion. Be that as it may, it certainly isn't for everyone, but it is very very special stuff.