Some chassis designs are heavier (in terms of cargo carrying capacity and towing) than others. USUALLY these are used on Diesels though.
In Workhorse the bigger the number the better the number (W-22, W-24, 24 is best)
When it comes to Workhorse/Ford/Freightliner/Other.. Different chassis builders often use different engines and transmissions,,, I won't discuss engines because all of them have their supporters, except to say I, Myself, am not a Ford FAN.
However on transmissions.. FORD, calls their latest offering "The Answer To The Allison" thus agreeing with the many (nearly universal agreement) that the ALLISON is the best transmission.. Who am I to argue? (Epically since I agree)
But as for the chassis itself,, I mean it's a couple of steel rails.