Downsizing from Home to 5th Wheel

Ha the 3 musketeers or mouseketteers replying. 
Any diesel dually will pull competently. 
We all have our opinions. 
Id suggest first making sure that you can handle a 60’ long 20klb truck and trailer. 
That will make or break this over what flavor of truck. 

Get the truck that fits your wifes rear end! or you'll never hear the end of it.  Leather seat for her, cloth for me! oops, can't get that option.....

I do not know how heavy that trailer is, so you might be into 45 series territory too! As noted, you need to know the hitch weight of the trailer. THEN< and ONLY then can you figure out what truck you need. A reg cab 25 series that is moderate to lightly specked, can have the same payload as a loaded DW crew cab diesel per the door sticker payload. My 2000 rwd 3 chargeable optioned reg cab vs my 2005 DW crew cab diesel truck. Both by the way were Chebbies! Reality, the DW rig had about 1500-2500 more lbs of actual capacity if I went by axle wt GVW vs the detuned basic gvw ALL of the manufactures work with. 

Speed up hills with an equal trailer, one of the three wins a few years, then #2, then #3, then back to #1 brand.....The actual real difference is pretty minor in reality. 

GM is typically the lowest entry rig, then Ram a bit higher, Ford the highest entry. If your short, or one of you has hip issues like my spouse, the lower entry rigs are a better option. If you have to lift or carry things into the bed, again, the lower bed height helps save your back. Probably one of the various and sundry reasons why I have preferred GM's over the Dodge-ram/Ford options.

Rear leg room for passengers, hard to beat the Ram Mega cab, Ford crew cab a bit shorter, GM crew a bit shorter yet. Unless you are 6.5-7' tall, probably in all honesty, you're not going to care about the legroom part in the back seat. Choose the seats for grand kids if you have them, favorite 4 legged creature that rides in the back seat etc. Or room needed for extra gear with the seat folded up.

Oh, and Red is the lightest paint color, so always the fastest, Black the heaviest, slowest everything else being equal.......If you believe this, Grit and I have a volcano or three rumbling in our back yards we can sell you!

Have fun shopping!

Marty

haha, that's nothing but opinion, I am going to say ford, grit is going to say dodge, and some one will say chev. 

all three are good, some have areas where they are better than others, but instead of telling you what truck to buy, figure out what the hitch weight of that 5th is, add 300 lbs or so and 1 or 200 for extra stuff and that will be the ballpark of your loaded pin weight including your 5th wheel hitch.  for example mine said 2300lbs but it actually spec'd in at about 2800lbs by the time you add the hitch and put your batteries in the front and such.  so make sure you have enough payload capacity for that, the people, dogs, fuel, and anything else your going to put in the truck.  

once you know that number you can go out and test drive all three and pick the one you like more as long as it meets the specs you need.