It depends on the use of the truck. If the primary use is placing standard sized loads (48" x 40" pallets) into and out of selective rack, the Drexel swing mast allows you to have narrower aisles than the Bendi and also provides for fast putaway/extraction rates once the drivers get used to the truck.

On the other hand, the bendi offers greater flexibility since it can handle non-standard loads (wider loads) and also works well for loading and unloading trailers (you can load and unload trailers with a Drexel, but it is a little more difficult). Though I should mention that its rather wasteful to use these more expensive trucks for frequent trailer loading. A bendi also works well in manufacturing areas where its turning characteristics allow it to snake its way through the narrow zigzagging access aisles commonly found in production areas. The Drexel will probably cost more in maintenance.

In either case, I suggest making your aisles wider than the minimum aisle widths recommended by the manufacturer. You'll find that minimum aisle widths on these trucks (especially the bendi) tend to be productivity killers.