I don't think the choice is as black and white as you suggest. I would say that some of the movements are more effective in the Ravel orchestration, and some more effective in the original.
For instance, Catacombae is a depiction of “Hartmann himself examining the Paris catacombs by the light of a lantern.” The numerous fermatas in combination with the subject of this movement, proves to be perfectly suited to the piano. The natural decay that occurs on this instrument, immediately after a pitch is sounded, embodies the very sound of a crypt. Moreover, the resonation of the sound proves analogous to the echoes that characterize the stereotypical perception of being in a tomb. Although, the introductory Promenade seems so suited to Ravel's orchestration that, in retrospect, the original cannot compete. Several more examples can be drawn to support each.
Re: the Great Gate of Kiev...I have to say that I prefer the piano, because one gets the sound of tolling bells...just like in Rachmaninoff's C# minor prelude.
Just my two cents.
- Andrew