Yeah this is tough. DMT is sort of the obvious choice overall, as it is just so special and powerful. But there are some real gems, notably DiPT (possibly the most unique psychedelic of all psychedelics), AMT (so good, also unique among tryptamines), and DPT (haven't tried yet but according to literally everyone it is amazing and among the very deepest and most powerful of psychedelics).
In past years I would have voted AMT for sure, not sure if I would today though. I might vote DPT, except I haven't tried it.