Kanki's death was well done but that's not really gonna decide the better arc
The tactics and strategies back then were more refined and detailed, the characters had great lore from Renpa and his HK, to Mougou and his two monstrous generals. It's a completely different tier.
Gian consisted of Kanki suddenly finding himself in Riboku's cage, we get shit dialogue for a dozen chapters, Kanki escapes and does some psychological tactics, Riboku miraculously escapes death for 6 chapters in a row
That's really bad as it gets in Kingdom, the dialogue was poor and without aim
I reread Sanyou recently, the first 6 days of battle, there is very little focus on tactics outside of Shin, Mouten, and Ouhon’s small 1,000 man units. It’s also hard to actually keep track of what is happening with the different armies because Hara’s POV shots were just off that arc.
The best tactical parts of Sanyou were Kanki vs Genpou/Kaishibou, Renpa vs Ousen and Renpa vs Mougou. Which are actually pretty small parts of the arc when you go back and reread. Most of the arc was related to the M3 vs Rinko and Genpou which just wasn’t that interesting for the most part.
Gian day one actually had great tactics. Shin and Kanki both had great moments to shine. Mouten got robbed but what can you do lol.
And Kanki almost checkmating Riboku was just thicc as fuck. I would take most of Gian’s tactics over most of Sanyou’s.
I also enjoyed the strategy and tactics with Hango. My issue with Hango is that Yotanwa, Shin, Ouhon, and Ousen basically got no love, but Riboku’s moments in Hango were fantastic, and the tactics with Seika were good enough, excluding Hara’s utter lack of giving Shibashou and Ousen direct hype moments.