Not toasted.
Chocolate Fudge.
I don’t break it in half. I like the crust.
I am now the proud owner of a 12 pack of strawberry frosted and a 12 pack of cinnamon and brown sugar. They were on sale for $3.50 a box. I haven’t bought them in 20 years but that seemed like a pretty good price.
Brown sugar cinnamon. Alas 
They make these little tiny square snacker ones now.
Grandkids like them in their lunches.
They are softer and fatter…good. The one I ate.
Seal in a bag and cook sous vide to 175 F. Carefully open and place on a warm plate on a bed of sweet rice with sweetened coconut milk. Frost if you like, then dusted with powdered sugar. Sear lightly with torch if frosted. Plate with suitable fresh fruit around to match the flavor. Strawberries are great. Slice across into 7 pieces. Eat with chopsticks. It’s like fruit sushi.
You are either a very creative BSer or a total nutbag. I’m not sure which is the better. 
Yeah, I’ll consider that next time.
Right now I’m biting a big corner off a cold one and using the aluminum wrapper as my napkin. 
This. 
(When I used to eat them: since my gastric bypass surgery, they have way too much sugar/literally make me sick. Sometimes I really miss a 2-pack of Chocolate Fudge, though!)
Strawberry, frosted or unfrosted, straight out of the package OR toastered for 15-20 seconds.
Blueberry. Frosted, because if I’m going to eat a childhood snack that’s stunningly bad for me, I’m going all the way. I break bits of the crust off and eat it first, then work my way into the filled area.
And I always realize about halfway through that they are really not very good, even taking nostalgia into account (I’m being disingenuous here: my mom generally refused to buy us Pop-Tarts because they were overpriced, bad for us, and really not very good. My memories of them are from other people’s houses).
My daughter likes the brown sugar cinnamon ones, untoasted, but she doesn’t buy them all that often anymore.
When I was a kid I really liked the brown sugar cinnamon ones. I haven’t eaten one in decades.
As an adult, I do like these knock-off ones, but I haven’t had these in a long time either. I do really try to stay away from the junkiest of the junk foods.
Cherry Frosted. For years I couldn’t find them in grocery stores (six-to-a-box), but I did see them in convenience stores (two-pack). No one else here has mentioned them, so maybe that’s not a popular flavor.
Like others, I have been trying to cut down on junk food, so I haven’t bought Pop Tarts for a few years. It seems like there’s a new variety every few months, and Frosted Cherry are back, so I’m occasionally tempted The last box was S’mores, which someone recommended. I figured if I was going to indulge, I should do it right, so I heated them in my oven. They were better that way. For many years, I ate them straight out of the box.
I do not break them in half. I’m a save-the-best-for-last type of guy, so I want those dry edges gone first.
Toasted as far as I can without browning the otherwise nearly inedible crust. So medium-short toasting, and you have to watch it.
Favorite varies - I can generally eat one Pop-Tart (1/2 a package) and like it, the second one I finish because I opened the first. Then I don’t want Pop-Tarts again for months. And I generally get the various iterations of ‘upscaled’ versions such as Trader Joe that actually taste a bit like fruit and less like chemicals.
I have a sneaking fondness for Smores flavor because I already expect those ingredients to be cheap chemically crap. And raspberry, because I -like- Raspberry but my wife doesn’t, so I don’t normally have that fruit or jam in the house. (she doesn’t object to the flavor, but the seeds are an irritant for her)
Never break - it tends to increase the already high chance of shards and fragments going everywhere, which is already likely when it comes to slightly more toasted versions.
Side for @Mean_Mr.Mustard - Strong agree, Toaster Strudel were far superior in every way as a “food,” but the need to keep them in the fridge and the need to apply the frosting made them less feasible as “throw in desk/car/backpack” for emergency work/school/etc snacking. And Pop-Tarts are always cheaper.
For those who wondered if their old favorites were still available: All Pop-Tarts® Flavors (poptarts.com).
Sadly the frosted ones are now the default and of 23 flavors, only 3 are not frosted: Blueberry, strawberry, and brown sugar cinnamon. Oldies but apparently goodies. Color me quite surprised to find them still making an item apparently mostly unchanged from 60-ish years ago.
Another vote for chocolate fudge, warmed a few seconds in the microwave.
Then cut into bits so that every bite has a good ratio of crust to gooey center.
All sweets are better with gooey centers. That’s why chocolate lava cake was invented.
I have never eaten a Pop Tart.
I love guava. We had a guava bush in the backyard growing up, and my mom used to make guava jam before she went back to work fulltime. I always order guava nectar when I eat at a Hawaiian restaurant.
Knotts makes a seedless raspberry jam that’s a staple in my house, because it’s my favorite jam.
Brown sugar cinnamon. Nuke to warm, then spread with butter like it’s a piece of toast. Oh, My.
I stopped eating them when they discontinued Frosted Dutch Apple 30+ years ago. I would toast them so the filling was scalding hot and would just take bites out of them until they were completely devoured.
Definitely any of the unfrosted ones are much improved with a slathering of butter.
I’m a brown sugar cinnamon guy, preferably warmed up. I think they only come frosted these days.
Of course today’s Pop Tarts are a pale imitation of the originals (and the Toast 'em Pop Ups of the time, which I preferred). We used to take them out of the toaster and slather them with Parkay liquid margarine.
I actually prefer Toast’Ems, a knockoff, to Pop Tarts. Anyway, I can’t really identify a favorite flavor, although when I was in my hometown as my father was dying a few months ago, that and bananas were the only things I wanted to eat.