Alicization is the newest edition to the Sword Art Online franchise, and one of its longest arcs, spanning from the novel's ninth volume all the way to the twentieth. It's so long that it would make Oda of One Piece fame jealous.
It's been a fairly polarizing series for several reasons; some loving the darker feeling tone and the shift in the main character, while others feel the series is starting to go off the rails, lacking the charm it had when it was first released. Both sides are entitled to their opinions, but, based on IMDB scores, Alicization has pumped out some of the better episodes in the whole series. These episodes will span both part one and part two, as War Of The Underworld is part of the same arc.
10 Stigma Of The Disqualified (8.6)
The episode is part of a multiple-episode string where the Integrity Knights, along with Kirito and company, are battling hordes of minions from the Dark Territory. It's an action-packed episode, as many have been in this string. The dark tone mentioned earlier is on full display here, as well, with many characters being introduced just as fast as they are being killed.
The biggest story arc in the episode is with Renly Synthesis Twenty Seven, a known coward of the Integrity Knights. We see him hiding away from the action, making you wonder why he's even there. But, in the end, he finds his courage.
9 Stacia, Goddess Of Creation (8.6)
This entire episode is based around Asuna's return to the main cast at long last, and that alone should explain the high rating. While she has her detractors, Asuna is a fairly popular character. Her return also has Kirito break down in tears, a level of emotion you rarely see out of the character. It made for a rather moving moment.
There's also a fun little skirmish between Alice and Asuna as they battle for ownership of Kirito. It's broken up before it gets too heated, but it was a necessary break from what was a fairly info-heavy episode.
8 Heartless Choice (8.6)
This is an episode your either going to love or hate, there isn't too much middle ground. It introduces some ideas many fans aren't going to be too keen on, throwing a lot of rules that were once in place right out the window, the first being the concept that you don't need a soul translator to get to the underworld anymore. It's a change that just feels way too convenient.
Second, is the one that's a little more controversial, it's that everything that's happened up to this point was to create Alice. Alice is a cool character and one this series needed, but this reveal wasn't handled particularly well. One thing everyone can agree on is that Lisbeth gave a very good and impassioned speech that was the best part of the episode.
7 In The Far North (8.7)
The episode is almost entirely about Alice taking care of Kirito and protecting him, a great role reversal from what usually happens in this series. As awful as it is to say, it's great seeing Kirito be helpless, forced to take a back seat for once. It helps let other characters shine.
There are a lot of callbacks in this episode, like the crossing of the two swords or the parallels between Alice and Asuna in the cabin with Kirito. Those types of moments take so little time to put in, but they enhance an episode so much. The animation in this episode, particularly the background, is amazing, too. Everything is so vivid and beautiful to look at.
6 Blood And Life (8.8)
This episode is all about Eldrie. Other stuff happens, sure, but he is the focal point, and with good reason. We see him have a great heart to heart moment with Alice, his mentor. It helps show just how much he cares about her, as well as how much his duty means to him.
All of this kind of telegraphs what's to come later, but it doesn't stop it from being absolutely amazing. His battle with DIL and subsequent sacrifice are all excellently done both animation-wise and emotionally. It's tragic when Eldrie meets his end in Alice's arms.
5 My Hero (8.8)
This episode is the finale to the first half of the arc, wrapping up Quinella as the primary antagonist. Their fight is good, Quinella pushing Kirito around for the beginning stages of the fight. While the fights important, the true heart and soul of this episode are Eugeo and Kirito's relationship as kids.
It's Eugeo that spurs Kirito further; his sacrifices and friendship are what help Kirito truly overcome Quinella. While people have died in this series, Kirito has never truly experienced losing a best friend as he did with Eugeo. Everything about their heart-to-heart and farewell was incredibly well done, making this one of the better Sword Art Online episodes ever.
4 Taboo Index (9.0)
This was a culture shock of an episode, taking this series to a very dark place. What happened here was something more akin to Goblin Slayer than anything we've seen from Sword Art Online to this point. It was jarring, even fans hoping for this tonal shift, mostly due to the content chosen.
Not only was this episode bloody as all hell, but there were even examples of bondage and rape. There have been undertones to it at times in the series, but, here, they dove headfirst into it—so far so that the episode was censored on just about every streaming service. It does lead to the moment of Eugeo breaking the taboo index, which is really important, but it just feels secondary to the dark material surrounding it.
3 Battle Of The Knights (9.0)
Many of the episodes leading up to this were exposition based, laying the groundwork of what was to come, sometimes to the point of boredom. This episode marks a 180 from that, going from mostly talking to pure action everywhere. We get to see a lot of the Integrity Knight back in action, as well as glimpses of the Dark Territory Captains, all of which look fairly cool.
The fight scenes are brilliantly animated, making both sides look incredibly tough. Fights themselves are also brutal, with people being cut in half, beheaded, and any number of other gruesome ways to die. There were also deaths on both sides, which felt necessary to add stakes, even if the hero deaths were more side characters.
2 Ray Of Light (9.1)
This is the last episode that's aired thus far, and it's one of the best. We got to see Asuna fighting for the first time in her goddess account, and she got to show off quite a bit of raw power, despite getting her arm cut off. We also got Sinon making her grand entrance, one that was far better than Asuna's. As a fan favorite, it was cool to see her back in action. You do have to wonder where Leafa is, though.
The other big development here was Iskahn and his forces joining together with the human empire. This is done after Vector sends them on a suicide mission, leaving them all to die as thousands of American players descended on the battle. It was an awesome moment since he was one of the better champions of the underworld.
1 Sword And Fist (9.2)
This episode features the best fight scene in the whole arc to this point, with Scheta facing off against Iskahn. The matchup is beautifully animated, as it has been all series and did a great job showing off how powerful both are. It will be cool to see the two of them fight side by side later in the arc.
The arc has done a good job of giving smaller characters their shine, particularly the Integrity Knights. It's cool to see their backstory play out, giving them more depth. At the very end, we see Asuna make her entrance, leading to an episode that's a little further back on this list.