Warning: Wall of text coming.
I’ve ranked all four Campaigns in several categories and gave 4 to 1 points each. The Campaign with most points wins. So here goes:
Gameplay/Levels:
Wings of Liberty - 4 points:
For me Wings of Liberty is a clear winner in this category. Every chapter is unique and original. You always have a lot of fun with all the main objectives that are vastly different in every chapter, as well as with the optionals that make you explore the whole map. For me, the Terrans are also the most fun faction to play. So the Wings of Liberty wins here.
Heart of the Swarm - 3 points:
This was a close one. Ultimately Heart of the Swarm is the second best, sure some chapters are reused mechanics from WoL, but the thing that made it better that LotV is Warcraft 3’s gameplay style of a hero centric gameplay. I find it really fun destroying the whole enemy base with a 55+ level Kerrigan. And also I find the Zerg more fun to play than the Protoss.
Legacy of the Void - 2 points:
As with the HotS, many chapters are reused mechanics from WoL and even HotS. While really interesting, I guess that Spear of Adun system is a bit less fun than Kerrigan. Also I find the Protoss the least fun to play, with all of their expensive stuff, and slow moving units. The thing that Prologue, main Campaign and the Epilogue are different from one another is kinda stupid. You already played the full Protoss tech tree in the Prologue, and then you have tutorial missions in the main. Kinda rediculous.
Nova Covert Ops - 1 point:
I didn’t like the gameplay here that much. Some chapters are basically a TPS, which I kinda don’t like. It’s obviouse that the Campaign was made after the canceled Starcraft Ghost FPS. I also don’t like that you don’t have some 30% of possible units, and the zerg coming to you almost all the time, with mostly weak Zerglings and Hydralisks.
Campaign Design/Structure:
Wings of Liberty - 4 points:
Again, Wings of Liberty wins here clearly. I just love the Hyperion and how it’s designed. You have four rooms, an arcade, news, people talking. Everything looks so lively. I just love the armory and laboritory systems, for you to choose on which type of units you wanna focus on. I love that there’s no turning back, so you have to think wisely. It’s awesome that you can choose whatever chain you wanna play, whenever, and you don’t have to stick with a mission chain like in other Campaigns. I also love that you have Zeratul’s mission chain, so that you don’t play with the Terrans all the time. The coolest thing, that other Campaigns lack, is choosing a mission. It just works well, and makes the Campaign more interesting.
Legacy of the Void - 3 points:
The Spear of Adun is a clear downgrade from the Hyperion. Only three rooms, and the Protoss behave like standing toys. The missions are spearated into planet chains, but not strictly following the chain, an improvement to HotS, but a downgrade from WotL. The thing that you can change your upgrades whenever you want is kinda a dull, and makes you not think as much, and not focus on a particular unit.
Heart of the Swarm - 2 points:
Again the Leviathan is a clear step down from the Spear of Adun. You have only two rooms and the characters there are more like toys. Kerrigan levels is a nice mechanic, however being able to change her abilities is kinda lame. I love the evolution missions and that you can’t change the chain, though. Also having to stick with missions of a single chain is kinda worse that being able to choose whatever chapter you like.
Nova Covert Ops - 1 point:
The Campaign doesn’t even have it’s ship. I mean it does, but it only appears in cutscenes. Both Nova System and Upgrades System is kinda lame to me. Why couldn’t you have both upgrades on a single unit, when you already did have that in WoL. Nova’s weapons and such also aren’t that good to me.
Story: (even I was shocked here)
Heart of the Swarm - 4 points:
Yep, a shock even for me. I hated it for the first time I played it, many things didn’t make sense to me, but now I think it’s story is the best of all the other Campaigns. First of all it has the best intro cinematic by far. Unlike other Campaigns, this one basically has only one character, Kerrigan, the others being almost non existent or her mind slaves. But it was done increadably well. You can really feel her character, her struggle between a human Sarah Kerrigan and the vicious Queen of Blades. I guess, I’m just a succer for that type of story, sacrifice everything to get your revenge, on one hand. And excepting who you are and use all of your assets on the other. It felt really good to finally deal with a big bady of Starcraft, and finally kill Mengsk. And the scene where Kerrigan, as Queen of Blades again, reunites with Raynor, and says something like “this is me, love me for who I am, or leave me”, pure badass.
Wings of Liberty - 3 points:
Yes, I’m a big fan of Star Wars. And Terrans being based on Starwars, it really felt like playing in the middle of Starwars. Like in Star Wars, you’re a rebel, an outlaw, fighting the evil futuristic, dystopian, dictatorship. While on the other hand having to deal with an alien invasion. Apart from Raynor, there are many other characters, Finley, Horner, Swann, Stentmen, Mira, Dr. Hanson, Tosh and Nova, Valeryan. And all of them are well done, and coordinate well together. I especially love Jim, how he becomes a heroic fegure, leading the rebellion and almost succeding, but being willing to throw it all away, so he could save civillians and people from the Zerg, and save the love of his life.
Legacy of the Void - 2 points:
Unlike WoL, here the chracters weren’t written that well. All of them are one dimensional, and frenkly some times even boring to watch. I don’t like the stuff about the prophecies of Xel’naga gods, the evil gods controling their minds etc… I think Amon is a weak villain compared to the Emperor Mangsk. I do like the part of all the Protoss uniting, but overall I’m not really a fan of this whole story. I’m generally also not a fan of super inteligent high tech alien stories, so that might be a factor.
Nova Cover Ops - 1 point:
To me the story was kinda lame. Whiping out the memories and emperial rebels that control the Zerg, like Mengsk did, kinda reusing stuff. I just liked this one least of all.
Visuals/Terrain:
Nova Covert Ops - 4 points:
Visually this one is the most stunning of them all. Every chapter was visually stunning and diverse, from the beach resort world, through a magical purple world, Zerg infested city worlds to grand imperial palaces. This one wins in this category.
Legacy of the Void - 3 points:
I really love the looks of all the Protoss worlds. Aiur looks stunning, Shakuras stunning and misterious at the same time, evil Tal’darim world and the sci fi flying Purifier World. I also love the visual destinction of the Protoss.
Heart of the Swarm - 2 points:
Zerus looks wonderful and awesome. The rest are kinda basic, Korhal looks awesome too though.
Wings of Liberty - 1 point:
This one is the most basic, some levels like the one where you destroy everything with the Odin or the space prison or the one where you mine terazine do look lovely, but most of them are kinda basic. I guess it’s cause this was the first Campaign they made.
Final Score:
Wings of Liberty - 12 points
Heart of the Swarm - 11 points
Legacy of the Void - 10 points
Nova Covert Ops - 7 points
TL;DR The winner is Wings of Liberty!