I have owned older Westies and vans, plus researched Vanagons and Eurovans a bit lately. The Eurovans seem to last, (lots of high-milers on ebay), but nothing can beat the interior layout of the Vanagon, (1980-91). As for air vs. H2o cooled, the later is a LOT better, IMO, in spite of some head gasket issues. If you can get a sorted-out waterboxer, they are great. Real heat and A/C, plus good MPG and OK power. (Both of these become less w/ Westy model and/or Synchro, mucho weight gain).
Having owned full campers and travelled in them, my favorite is now a regular Vanagon w/ folding bed and table, (either a Wolfsburg Ed., Carat, or any '89-'91), nice low roof clearance for parking ramps, less weight and (slightly) better aero, all you need is a cooler, cell phone and laptop w/ DVD player and net card, BINGO! you've got a live-aboard!
