Truck Forums - Looking for opinions on 2009-2011 GMC or Chevy extended vans

Hi, thanks for taking the time to stop by. I'm an expediter currently in a 2006 dodge sprinter 3500 and I'm thinking about switching over to either a Chevy or GMC extended van. I would like any and all comments good or bad about them. I might look at a used one no older than 2009 or 2010 if I can find one with low miles, or a new 2010 or 2011. I would like suggestions on which motor will hold up the best for high miles say 300,000 or more and also heavier loads. I'm not interested in a diesel again. Also what kinds of fuel economy should I expect to see with the different motors, I don't have a heavy foot for acceleration but I do usually like to travel about 8 or 9 miles over the limit. I also am not sure if I should go with a 2500 or 3500 at this time. I'm looking to buy some time just after the first of the year. Thank you in advance for any and all suggestions.