I think the best way to compare resale vs. resale is by maintenance fees vs. what you get for those fees.
It's hard to argue something that costs $1 + closing costs won't hold its value when resold.
However, would you rather pay $500, $800 or $1,000/year in fees? And what do you get for those fees?
As long as everyone is honest

and you get similar value for you fees paid, higher fees would mean a better resort (more staff, bigger pool, whatever). Those things cost money. If you aren't paying higher fees, don't expect more from your resort. This could be a good argument in favour of DVC (remember I own on Int'l Dr, not DVC).
Obviously watch out for the converse: paying higher fees without getting the benefits of a better resort.
I'm OK with the fees I'm paying ($600/yr I think) for a 2BR, brand new pool. I still wished I'd bought resale, but I'm not going to beat myself p for having made a mistake, and I can't get what I originally paid the developers. I have thought about selling mine and buying another, but I'm not sure I'd get value for my fees paid.
If no one has suggested this already, try renting someone else's timeshare at a place you're considering before you commit. You can also get good deals by agreeing to sit through a 2-hr developer sales pitch but WATCH OUT - that is how I ended up buying mine. I bought it because it made sense at the time... but buying resale would've made even more sense for all the same reasons.
I still haven't made up my mind about DVC... I think the individual tastes and situation makes a big difference. Right now my non-DVC works well.
Finally (gee I love my own voice

) consider points vs. weeks. DVC has points, so do others. I originally bought 1 week every two years, but upgraded to points for 1 week/year (planning for 2 weeks every 2 years to save airfare). There are lots of advantages of points, and I expect they'd be easier to resell (from my own justification, anyway). However that could mean re-sale weeks are getting cheaper than points - because people prefer points and won't pay the same for a fixed or floating week.
I like points because I can travel through the week, say arrive Tuesday and leave the following Thursday, to get even better deals on flights. Can't always do that with weeks.