In the OPs case both would have the same radiator location, regardless of chassis choice. Both would have Comfort Drive, and the same axle ratings. I would have to check on rear end gear, but I would assume they would be the same.
**Update**
I just checked, the Freightliner has a higher rear end gear (lower number). Based on this I'd go with the Freightliner simply for the better MPG potential, although it probably wouldn't be a big difference.