Alright, I will list some of my favorite maps from Legends of Arkain: True Story. Specifically, the First Book portion of the story.
Rise of the Clans: What I enjoy about this map is that the player is given a choice to select one of the three Orc Clans (either Deathbreeze Clan, Darkmind Clan or Goldaxe Clan), each with different objectives (for Deathbreeze, it would be destroying the bases of major clans; for Darkmind Clan, it would be to subjugate the minor clans; for Goldaxe, it's simply to gain a certain amount of gold). I am usually serious and focused when playing Arkain, but with this map, when I chose to play a Goldaxe Clan, there is far more freedom to do as I please. I can go around and kill some Boar Regiments goons or I can simply walk through the map, doing nothing, while my peons gather gold, whilst maybe investing in some mercenary contracts along the way. If I want a little more action, I can gather my forces and extort some minor clans. Overall, it's simply a more "laid-back" and undemanding map (if you play as Goldaxe, that is), I can (mostly) do whatever I want, unbothered by major clans and their attacks (up until Rangul pays us, of course). It's usually the map I play the most, usually whenever I simply want to relax, take my mind off things and just kill some time.
Pride of the Empire, Betrayal and Bloodbath: The great, intense and dynamic battles of Arkain with lots of killing, bloodshed, slaughter, destruction and high-octane action. There are AI allied players, lots of enemy bases to destroy and an occasional Firelord along the way. In general, my favorite maps are these big penultimate and/or climactic showdowns that occur near or at the end of their respective "eras" (the aforementioned three chapters for the First Book/the Fall of Lor era; Purificator maps for the Second Human Book; Risen Resistance, the Red Day and Warriors of the Dominion chapters for the Second Orc Book). Rise of the Clans is my relaxation time, while the final chapters of the First Book era, and the penultimate/final chapters of the Second Books are a true rock 'n' roll.
Honorable mentions:
Night Hunt: A more stealthy mission with a dark and eerie atmosphere, from the mission taking place at rainy midnight, the Undead user interface and music in general, orcs talking about the chieftains of Bronzeforge, Silvertooth and Brassfist clans not having been seen for quite a while (it was never exactly made clear what happened to them, they could have been disposed of i.e. killed for all we know), references to a some sort of mad preacher (that mad preacher of course is one of the more benevolent orcs, but the other orcs talking about him before we are able to meet him still contributed to that chapter's ambience), to some the Duskbrand Clan warlocks believing that something bad is going to happen. Out of all True Story maps, this map is the one to come closest to a more ominous, uneasy aura that I thought Arkain Books had (it's a different matter entirely, but in general I think that Arkain books had a more foreboding feeling that was not quite replicated in the True Story, though it's only my own opinion and perspective).
Bloody Uprising: It's a chapter that I simply drawn to, even if it's not the mission that immediately comes to my mind when I think about my favorite maps. It's kind of like Rise of the Clans with Goldaxe in a sense that I usually play this map when I want to relax, but unlike the said map, things are more brutish and tense. I like to attack the Goldaxe-adjacent clans or have them clash with the minor clans. I also enjoy that the subjugated minor clans join you in attack your enemies (primarily the Blackrazor Clan). Having an undead spirit of fallen chieftains is also a neat touch. Last, but not the least, the conversation between Iszhog and the Destroyer, with the former being the first character on-screen that the Destroyer seems to take somewhat seriously, even being somewhat wary of (in contrast to his proud, boisterous attitude towards other orcs).
Carnage: Playing as the Demons and controlling Kersidar alongside the Souleater Servants was quite a pleasant surprise. Bringing the painful end to remaining enemy forces was pleasing. I will admit that this chapter actually felt macabre, yet lighter in tone than the Bloodbath. The final cinematic of the previous chapter, particularly the part where Lokar laments the loss of his chieftain, felt dangerous, tense, with a looming threat of Demons on their way and the Destroyer making his stand against him, yet when we play as the Demons, there isn't that sense of menace and the chapter ends up with a quirky goblins coming to take Destroyer, while he is fighting against the Eliminator. That's not a criticism, just an overall feeling I got when playing that chapter (then again, fighting against the Demons is more scary than playing as them). Since this chapter is meant to be the end of First Book/the Fall of Lor era of the True Story, it's cool that the final moments were with the Destroyer (an orcs) and the Goblins (hired by Okri) rather than a non-orc/non-Dominion characters.
Interludes:
The Council of Generals: Despite the humans being my least favorite race as a whole in Arkain (in general, I am somewhat fatigued with the humans taking a central role in Warcraft, both the official canon and fan works, and fantasy in general), I will say that I do like the plot point of there being a traitor within the Imperial Ranks and I always felt that this interlude began to build-up the tension and forewarning. The True Story had also introduce a segment where Genethas was trying to convince others that Gardon was the traitor and one could see the signs of Genethas' odd behavior: Genethas openly stating his suspicions, then backing away with a rather shifty "err" and then claiming that this simply an assumption (after Kenos says that it is dangerous to speak about these kinds of things without further proof, then asking Genethas if he agrees). I also recall that some fans noticed that while Gardon kept suspicions to himself, but worked to investigate whether there is indeed a traitor, Genethas proclaimed that Gardon may be traitor, but made no attempts to look into any possible signs of a traitor and gather any useful information. This interlude also sets-up a journey into the underground tunnels, which paves the way for Aedale's corruption, which I felt was an ominous plotline in the First Arkain Book.
Blood and Death (honorable mention): It's just simply an interlude that I like. The conversation between Destroyer and Rangul, the Destroyer briefly looking over Iszhog and the introduction of Okri. I also like that while the focus was given to the Undead and Genethas vs Aaron, this interlude was primarily orc-centered.
A Shadow of the Past: A True-Story interlude that I really enjoyed when it came out. I liked that it focused on Vanessa and that it showed the interactions between her and Iszhog (who had shown his friendliness and hospitality to Vanessa), and of course, the conversation between Vanessa and Amari. It was nice seeing them together and it's good to know that in the True Story canon they knew of each other and were friends when they were younger (unlike in the Arkain Books, where Vanessa only learned about and met Amari only in her early adult years). Act 4 had two human-based mission, two undead mission, but only one Orc mission and this interlude gave something to the Orcs.