Hi. First, I'm really excited to announce that my old gaming group from college is reuniting! (Yay for me.)
In our individual groups, splintered across several cities, we each have played several of the APs: Shackled City, Rise of the Runelords, Council of Thieves, and Carrion Crown.
I'm looking for the one to try next. It's not essential for it to be PF (I can convert from 3.5), but it would be great if I can purchase print copies.
I did pick up the first volume of Jade Regent, and I was a little disappointed that it seemed to have a long "wait period" to get to the "good stuff." It seemed from the outline that the first several adventures are just collecting information before the party gets to the exotic locales and really experiences the adventure.
How about playing bad guys? We put out the ENnie-award nominated "Way of the Wicked" campaign. You can read all ten of the reviews of Book One right here and judge for yourself whether it starts out strong.
If being wicked isn't your thing, how about Kingmaker? Its sandboxy, build-your-own kingdom vibe is great and very different from the four you listed.
Well, I guess it depends on what you consider the 'good stuff'. What type of campaign are you looking for? Are they big on the action or the roleplay? How do you like gobs of NPCs about? Each AP out there does good at focusing on a different theme, even if multiple ones are in Varisia.
A couple examples
We're partway through Jade Regent, and honestly it was great from the start. We gloss over a lot of the caravan stuff now, and skip random encounters, which helps keep up the pace. It is definitely Tian-Xia themed and even from the get-go hands out Tian treasures. There's also a lot of travel, especially in very cold areas.
I'm running a Crimson Throne group, and my players seem to be enjoying themselves. The first few chapters are really good, and there are lots of GM notes to help out for some of the 3.5 adjustments. It is heavy on the urban side for the first several chapters but don't be fooled, at least two chapters take you out of the city for some railroading.
A different group is playing Serpent's Skull and that's had quite a bit of fun as well. It's heavily jungle-based and very different from our Crimson Throne campaign.
Legacy of Fire is a nice one, though it's 3.5E and finding a print copy might be tough, it's my favorite so I guess take that with a grain of salt. Skull & shackles looked like a lot of fun, though I hear it activates Hard Mode right away.
If you want an AP that gets right to "the good stuff," I'd recommend Shattered Star. Your goal and purpose is very clear from the start, and from the first adventure you are picking up artifact-level items, fighting powerful foes, and exploring the decaying but still amazing remnants of Thassilon. It is very dungeon crawly, but when each of those dungeons feels like the final amazing discovery of a long campaign it works out.