Harley guys talk about resale about as much as anything else, but I don't have a clue. Ducatis definitely hold their resale, and I think Triumphs do pretty well. I know a guy here that rides a Daytona and he said the customer service at Triumph dealerships are infinitely better than any other he's dealt with. I'm sure BMW is the same way.
Talk to Saint, I know he's researched a lot of bikes in the past year or so.