I will do that today too, but since there's a bit of a (completely unwarranted) controversy with this ship I will also talk about that. BUT love takes priority, so I'll share my views on the ship and its dynamics first.
First of all, this is probably the best named ship of them all. Straight up Apple Pie. It works so purely and easily XD. But now to the real reasons. Pinkie Pie works about the same with most the ships she's in. A classic goof/comic and straight man/stooge duo. Apple Pie is no different, the main difference I see with these two over ships like TwiPie or RariPie or PinkieDash is that Pinkie isn't just a silly gal that the other has to sorta "put up with" in a lovable way, but rather, Pinkie is the one who breaks AJ's mold and monotony. Applejack is a mare of tradition, hard and constant work, and routine. Pinkie Pie comes by and interrupts this with joy and giddiness. She's a welcomed wrecking ball, the spice of life. On the other hand, I feel like Applejack could be the one who could listen to Pinkie Pie the most when she needs to be taken seriously.
They also share a ton of interests and hobbies. Both are very talented musicians who like learning and playing several instruments, they're both amazing cooks and specifically bakers and pâtissières. They both are very family oriented and know about farming and the farmer's life… In other words, I feel they could not just enjoy a fun relationship for a while, but also long term goals could work and improve in tandem very well. They have a synergy of desires and aspirations. They don't have the issue these two have when shipped with Twi, Rares or RD, where the aforementioned 3 either want or are expected to expand or leave Ponyville in order to fulfill or pursue their desires/obligations.
All in all, I just feel they're a really good ship that can work, play, live and grow together, feeding off the other's momentum to better themselves.
Now to address the elephant in the room. The 'incest' controversy. "But Gutovi!" you may say, "They are cousins, there was an episode about that!". First of all, it was never confirmed fully, it was dubious as best. But even if Pinkie read it right and they are indeed Fourth Cousins Twice Removed, I wager you don't really understand just how unrelated that makes them.
Here's a pretty handy video, but if TL;DW…
It means that they share a GreatGreatGreatGrandparent AND, either of the two lineages (I assume AJ's considering how the Apples seem to reproduce) is actually 2 generations further down the line from the other which means that this common relative is not a GGGGrandparent to both, it'd be GreatGreatGreatGrandparent for Pinkie and GreatGreatGreatGreatGreatGrandparent to AJ. You may not think that is too wild, but like, think back at your own lineage. Odds are, already by Great Grandparent, half of them were from different parts of the world, imagine going two more generations back, or four! Considering something like this, there's probably about as much bloodline connection between Applejack and Pinkie Pie, than between you reading this, and me.
I doubt even medieval noble houses who were all about preserving a bloodline would even consider that to count unless everyone else in the family tree was dead XD
Not to mention they're both girls so like… 75% of the reasons incest is considered problematic is a non-issue here.
Now, say we move past this and yet you still tell me: "But Gutovi! It doesn't matter if they're or are not related by blood, they considered themselves to be like family, it's weird!" Now that's probably the easiest to dismiss. Most very close friends will treat each other or even call each other like family, and when feelings start to show it's not hard to realise it was all just a ruse to handle those close feelings.
Anyways, I love this ship, I love these two even when not shipped, and I'm happy with this piece. I hope you are too!