Shirou fighting off not one but Two Sekirei, one almost got her leg sliced off and the other's weapon got destroyed and she got some injuries, Shirou on the other hand wasn't even scratched. It was so Awesome that all the other combatants stopped to gape in shock at Shirou. Topped by him quoting Souichirou Kuzuki, who pulled the same feat on Saber during the 5th Grail War. That's how a fight is supposed to go and no wonder Shirou was disappointed on how his fights went so far.
Twenty Fifth Wing, not just because it was a long-awaited action sequence in the middle of character building chapters, but Shirou's whole plan to defeat the nameless Fraga magus once Miya was taken out.
Planned as follows:
1) Lead the magus around using sword spam to an area where he can backstop his attacks and reduce overall property damage
4) Repeat step 3 until opponent is out of Fragarach, since you can create a near-infinite amount, courtesy of Unlimited Blade Works
Bonus points because it was only viable because he saw how Miya was taken out.
The single, specific moment in that whole sequence: Shirou has set up Crane Wing Three Realm and launched it. The enemy counters with Fragarach, and watches with anticipation for Shirou to be cut down by his own attack. Then:
Thirty Fourth Wing: Rematch between Shirou and the two Sekireis from above. Result: First case of a Sekirei being LEVEL FIVED and the first case of a Sekirei being known to have been terminated by an Ashikabi. The Disciplinary Squad members (outside Karasuba who at that time was about to enter the location) were speechless.
Thirty Seventh Wing: It took 30 minutes for Shirou's flock to assassinate Higa, storm his headquarters, kill his secretary, recover the Jinki, rescue Yukari, blackmail MBI, and get away with it all. It is AWESOME.
It gets better, the above mentioned assassination was also a call back to earlier in the story when Shirou claimed he could bullseye from a mile away.
Even his mother was impressed, even if she tried to not show it. And Karasuba is now even more eager to fight him (and was teasing Shirou to make him give her a "souvenir" even in Takami's presence, which means that Takami likely realized Karasuba has hots for Shirou).
Offscreen moment for Shiina. Shirou and his flock arrive to save Yukari, only to find a floor full of half-dead security guards. Turns out Shiina beat them there and pretty much steamrolled everyone between him and Yukari. He caps it off by carrying her out princess-style and getting Shirou's blessing for their relationship.
Forty-First Wing: Shirou defeats Saber using an imperfect replication of Assassin's Tsubame Gaeishi technique as a distraction, followed by a surprise flying sword to her spine, despite losing an arm in the process. He then proceeds to use the Hanaya Mask to surprise Rin who had taken him by surprise with her Gandr Shots, and forces a geas on her that prevents her from ever seeking him out again, and likewise for him, essentially enabling Rin and Saber to return to the Clock Tower without consequence.
Forty-Third Wing: In short terms, the whole. Damn. Chapter. In long terms:
Shirou vs. Karasuba.
Shirou winging Karasuba after using Rule Breaker on her.
The big Sekirei fight that Shirou and Karasuba are involved in as a whole.
Mutsu batting away the swords that Shirou sends flying at Mikogami.
Shirou vs. Minaka.
The cliffhanger ending, with Shirou summoning Excalibur in a last-ditch effort to stop a potential catastrophe.