Is is a warehouse/indoor or outdoor application?

Stand-up trucks are usually used during the indoor operation, in warhouses, where the surfaces are smooth, and the space utilisation is meaningfull.

Rider electric trucks (excluding reach-trucks) are mostly intended for indoor application, but out of rackings, IC rider trucks are for outdoor work, where surfaces are sometimes rough and the distances are longer.
I think, the decision should be made basing upon application.
The stand-on counterbalanced trucks are pretty rare in Europe and are being used only in very tight areas.

If the choice is like: warehouse, high stacking + sit-on reach truck or stand-on stacker, I'ld take the reach truck (if the aisle width allows). it's definitely more comfortable and safe.