but really, I prefer the piano original to all of them.
Indeed :)) Dear old Modeste never gave any hint that it was any kind of 'unfinished' orchestral work... and as you rightly say, his faithful collaborator Rimsky never took on such a project :)
There are more than 600 orchestrations of this fabulous work (including one by yours truly which lies somewhere between Tushmalov and Ravel and includes an organ in the final moments). Someone actually has a catalog of all extant orchestrations. The work is so imaginative that many composers "hear" a version of this work and take it upon themselves to orchestrate it themselves. It would have been very interesting to know how Mussorgsky would have orchestrated it because he did conceive of it orchestrally (he has a crescendo in a whole note on the piano which makes sense only if he intended to orchestrate it). By far Ravel's magnificent treatment of this material deserves its place as "The" orchestration. It casts a long shadow on anyone attempting to orchestrate this after him. But he also removed some movements that do seem superfluous but ignores Mussorgsky's intention. In my opinion he greatly enhanced the work by removing some of the extra promenade movements though some orchestrators and arrangers felt restoring them was more truthful. Ashkenazy has a very fine orchestration which most will consider more Russian than French so also very suitable. In my opinion, the merger of French and Russian produced some of the very finest works so the mixture of the French refinement with the Russian coarseness is perfect. Sort of like how an excellent meal or wine is balanced between fruitiness and tartness.
If anyone is interested in hearing, here is an excerpt from my version:
http://picosong.com/wnby9