I've subscribed to all of these at one time or another and I would rank them like this:
1/ Conde Nast Traveler
2/ Arthur Frommer's Budget Travel
3/ National Geographic Traveler
4/ Travel + Leisure
I think CNT has the most interesting stories and trip reports + good travel industry info. Budget Travel is skewed a bit more to just that, and I'm not necessary looking for the cheapest property anymore. NGT has more stories and narratives.