I’ll limit it to season 8, which I still enjoyed, warts and all. I leave the main story line (apparently coming from GRRM himself) intact as well.
No major changes to episodes 1 and 2, except clarifying that Dany left a considerable force of unsullied and dothraki in Dragonstone to prevent Cersei’s forces from capturing it.
Episode 3: my main gripe is the plot armor of most (co-)leading characters. I’d have Samwell in the crypt, not at the front - he can lead the defense against the wights raised there, which is far more believable than him surviving wave upon wave of bloodthirsty wights. Brienne, Podrick, Tormund die defending the castle. Rhaegal dies in the fight with wight Vyserion. I’m OK with the rest, except I would have Arya sneaking up to the back of the night king rather than jumping from wherever. Having the NK do a swordfight with Jon does not make sense - why would he?
Episode 4: the weakest of the season for me. Changes: Jaime still leaves for KL, but also because Brienne is gone. Euron’s fleet still sets the trap, Dany spots it, but a few near misses from the scorpions makes her back off. Euron destroys Dany’s fleet, captures Missandei and decapitates her there and then, her head washes up to the shores and gets found by GW. No negotiations at KL, while standing in reach of the scorpions. Dany makes a reconnaissance flight with Drogon of KL and spots the danger points (scorpions, but far less than in the series). The war council decides how to attack KL and the whole bells thing (shifted from episode 5).
Episode 5: Jaime arrives in time at KL before the gates close and goes to the room with the map on the floor. Dany and Drogon take out the scorpions, and burn Euron to death, while the Golden Company does something for their money, engaging the attacking force. Strickland and GW battle and GW wins. At that moment, Dany destroys most of the remaining GC soldiers and the attackers advance into KL. As the bells sound for surrender, we zoom in to the changing faces of Dany and GW, alternating, suggesting that they had agreed on this beforehand. At the same time they both resume the attacks and the carnage follows. Less shots of Arya, the Clegaynebowl happens as in the series.
Episode 6:
I’d keep this pretty much the same upto the Dany/Jon encounter (except GW does not execute the prisoners, but another unsullied). More time for the encounter, more discussion between the two, Jon giving her more time to make him change his mind. In the end, he still kills her. I love the Drogon reaction (dragons are supposed to be highly intelligent, and it shows in this scene). The council meeting a few weeks later will include Jon as prisoner (just like Tyrion). Bran will do the talking initially, highlighting the need to elect a king/queen. He’ll ask for candidates, and after Edmure gets shot down by Sansa, no-one comes forward. He then suggests that Tyrion, who has served as Hand on both sides, makes a proposal. Tyrion points out that Jon is the most logical choice, but before GW explodes, Jon refuses, stating that as queenslayer he cannot do it, and he does not want it anyway - he volunteers to take the black. Then Tyrion suggests Bran, with the same outcome as in the show. Instead of the meeting of the small council later (which was one of the lowlights of the episode for me), we see Thyrion as hand discussing with Bran who should be on the small council (including Bron to close that arc). Bran agrees with all proposed names and says “I must go now” flipping his eyes away. The Starks’ goodbye scene and the rest of the episode stay the way they are (obviously without Tormund).
