It's crazy to think the Fate route had the best final fight, all things considered. Two 1v1s, with Kirei getting Azoth'd and Gil screaming Seiba's name out as he jobs for the first time in the story.
UBW is okay depending on the medium, but all it really amounted to was Archer somehow coming back at the last second to save teh dae. If anything the Assassin battle felt more climactic and well-written
HF is in some ways better but worse in most. Kirei boxing match was cool and so was Sakura's breakdown and Zouken's revelation, but the Zelretch scene was the most blatant example of powerscaling beamu BS in the entire VN. Seiba v. Ridah was also undercooked
In reality the biggest problem in the VN is that the action peaked halfway through, ie. when the route-centric reveal had just happened. Seiba v. Basakah, Shirou v. Archa, and the Medusa reveal. Dark Sakura happens so late in HF that I'd hardly call it a peak.