which is better choice, used full size

03 Silverado v6 @ 64k mi
03 sierra 5.3v8@55k mi
06 ram v6@54k mi

All 2wd reg cab

pros cons, opinions, anything?
thanks  

Silverado v6 is a very well engineered vehicle, and known for lasting a long time.  I personally drive a Silverado and I was looking for a Dodge. In my opinion, Chevrolet Trucks are a very nice truck, also they are also very technically advanced over Ford.  

2005 Gmc Sierra X-Cab longbed, 170K miles.....
5.3 V8, starts every day without issue, still get 19mpg on the freeway, no issues other than a water pump about about 125k.  Alignment is perfect, well after 3 years of abuse.  Truck has hauled up to 10,000# between bed cargo, trailer and trailer cargo, granted, not a speed demon up the hills, but it does it.  Original transmission and everything else.  Has been VERY TROUBLE FREE.
Problems with truck currently:
CD Player doesn't work.
That's it.
A/C Still perfect in California, too.
Just passed emissions with flying colors.
Nothing other than normal maintenance, plugs at 100k, oil changes, brakes, tires, etc.  And trust me, truck has not been babied!
No rips in interior.
Have owned nothing but GM trucks since 1994 and have put a boatload of miles on them, towed trailers for thousands of miles, all with NEVER being stranded.
Would I hesitate to buy any other GM Truck?  Absolutely not.
I would do the 03 with the 5.3 myself.  The 4.3 is a fantastic, albeit archaic motor, but, it gets you down the road for 200k+ easily.  The 5.3 should do the same, it'll just haul more a little faster in the process.  

Any of those would be fine, but I'd probably lean toward the Sierra with the 5.3 Vortec. It gets about the same mileage as the 4.3 V-6, but with MUCH more power. Historically, the Ram V-6 has been underpowered & thirsty. Even though it has more power on-paper than the GM 4.3, it has less torque, which is what you want in a truck.  

Any newer 2002 and up GMC Sierra or Chevy Silverado with a a 5.3 or 6.0 will do the job for a lot of years too come. Mileage might be a consideration.

I had a 2002 GMC Sierra SLE 2500HD 4X4 long bed. it had a 6.0 and 4l80E trans. In 2008 most of my older buddies and myself were going to retire in a few years. So we decided to take our race cars and go do the western tour. That truck was loaded to the hilt. 4 guys and some that could go on diets ...LOL... All our clothes, 2 race cars all the spare parts we thought we would need, the bed was full also. That truck averaged 15MPG on that 2800 mile trip. It went over the hills in Colorado in OD. I let it shift the way it wanted to. I'm saying that these new engines that GM puts in these newer trucks out pull the Ford and Dodge. Ford and Dodge can say what they want, but they will never convince me of that.

In 2009 that truck saved my life. I was stopped when a drugged and drunk punk hit me head on at 80 to 100 MPH. The police guesstimated the speed as there were NO skid marks from his car...It's a very safe truck also!!!!  

i can suggest sierra 5.3v8 . It would be good choice.