This question gets asked all the time. But that's ok, my answer remains the same. The most visual psychedelic is whatever psychedelic you take a significant dose of.
There are plenty of psychedelics with the ability to turn your world into complete visual soup if you take enough. Or if you take enough to create an ego-death experience, usually you are also totally washed away in visuals.
Some psychedelics have more side effects which make them more difficult to take an extremely visual high dose, and others like LSD, DMT, DOC, DOM, Psilocin, 2C-E, etc can be very visual at relatively comfortable doses.