I didn't really have time to share my choice before clocking out yesterday but after thinking it over, I am going with the 2007 as my year. Aside from being insanely affordable compared to the prices of today, I considered the following:
Disneyland Pros: Attraction line-up is probably my favorite overall and things are looking good and refreshed coming off the heels of the 50th anniversary. Haunted Mansion Holiday is a thing, Pirates of the Caribbean and Tom Sawyer's Island just got their movie additions (I like them, sorry!), Big Thunder Ranch, longer Rivers of America, Splash Mountain, Snow White's Scary Adventures, Innoventions, Disney Gallery in New Orleans Square, Carnation Plaza Gardens and Star Tours 1.0 are all still around. There is a show playing in the Tomorrowland theatre still with "Honey, I shrunk the Audience". Indiana Jones still has a working Chamber of Destiny, "it's a small world" hasn't added Disney characters quite yet. The Submarine Voyage has just reopened for the first time in years. Parade of Dreams, Fantasmic! and Remember... Dreams Come True makes for an unmatched entertainment line-up. Matterhorn has it's original seating configuration and it's original yeti (I do like the new additions, admittedly but it would be fun to say hello to the original again). Halloween Time is just starting to pick up steam as a popular offering. Both Space Mountain and California Screamin' are offering unique experiences for the first half of the year with their "Rockin'" iterations. Fastpass service is free and it's original incarnation.
Disneyland Cons: Ghost Galaxy hasn't materialized yet, but given how it seems to be gone forever now, I would consider this a wash at worst. Park wasn't
quite there with it's foodie revolution yet. Some locations were experimenting with moving away from the same sorts of generic offerings but it wasn't across the board just yet (Jolly Holiday was still a sort of generic passholder processing center, I believe). Though I would not complain if I got to experience French Market's fried chicken and steak fries once again! Mickey's Toontown had a lot of it's play areas closed off due to safety concerns during this time. Great Moments with Mr. Lincoln was sidelined for "Disneyland: The First 50 Magical Years". The Sleeping Beauty Castle Walkthrough wasn't ready yet and Fantasmic! hadn't seen it's major upgrade yet (though your mileage will likely vary on this one).
DCA Pros: Again, an attraction line-up that actually makes this a full day park for me. Monsters, Inc., Tower of Terror, Aladdin musical, Muppet*Vision 3D, the Animation Building has ALL of it's features available during this time (Beast's Library and Ursula's Grotto), It's Tough to be a Bug!, original California Screamin' (with Rockin' version at the beginning of the year), Soarin' over California full time, Grizzly River Run, Redwood Creek Challenge Trail and of course, the Mission Tortilla Factory! Shout out to Heimlich's Chew Chew Train, too.

At this point in time, DCA was also still sort of a "red-headed stepchild" compared to Disneyland so it meant that crowds were better. -and again, original Fastpass service.
DCA Cons: A lot to unpack here, I suppose. Obviously the end of this year is when Disney would announce the new direction and giant overhaul for the park. So while this year is technically not the park's "best" in my eyes, I think it's offerings during this time while paired with Disneyland of the same year make it a solid choice. Sure, we are missing the objectively better Buena Vista street, new Soarin' area, Little Mermaid, Midway Mania!, Paradise Garden Parks, etc. but at it's core, this year of DCA still offers most of what I loved to do in this park albeit not wrapped in the prettier package. Same with Disney during this time, DCA had also not yet fully stepped their food game up (No sun dried tomato pasta!

).
I could probably go on and on. But yeah, I think 2007 wins it for me and really drives home what I see in my mind's eye when I close my eyes and imagine a "perfect as can be" trip to these parks.