I've used all major DR airports (except Barahona), in both commercial and private aircraft.
1. Clearly, arriving on a private jet @ the now reclassified Herrera airport with the driver of your own car waiting at the hangar is tops in terms of the moving-right-along-on- time factor. Short of that close-and-personal service available only on special occassions or for a lucky few, then Punta Cana, La Romana, Santiago and Puerto Plata are all equivalent in speed, from tarmac to the 1st roadside Presidente. SDQ is not that far behind in speed unless you're arriving from Colombia or Panama. Searches for contraband focus on planes arriving from those places rather than Miami, New York, or Madrid.
2. Flight safety. Most aviation accidents occur at landing. By virtue of its geography, STI would be less favorable than airfields set on ample, flat, oceanside areas with small populations (like in PP, LR, PC and even Cabo Caucedo's SDQ). Any pilot will tell you that emergencies are more easily handled away from a densely populated valley surrounded by high mountains, as in Cibao International. Otherwise lovely place.
3. Services. Like the people of any big town, the workers at SDQ seem to be the most indifferent to travelers' questions. Tourist area airports unabashedly cater to their visitor, as it should be, so that POP, LRM, and PUJ have an edge on SDQ and STI, although people are quite friendly even on these last two. Keep in mind, friendly is not always equate to effective/productive/useful/able.
4. Fundamentals: see Laszlo's post above.
cheers,
- Tordok