All the little moments that show how close the men were. Examples:
A group running up Currahee with their buddy after he was sent there for punishment.
The lengths the men go to to rescue their wounded comrades.
A morbid example, but the way the men all jump into action to find the man who shot Chuck Grant.
Harry Welsh lugging his reserve chute around because he wants to send it home for Kitty, to be made into a wedding dress. Yes, he did send it home and he got home to marry her as well.
In the final episode, "Points," teetotaler Richard Winters posts a couple of guards in front of a Nazi bunker - specifically Hermann Goering's house - to protect its contents from looters. . . then tells his friend, the hard-drinking Lewis Nixon (who has been complaining recently about not being able to find his favorite whiskey), to grab anything he wants from the massive wine cellar, then tells him that it's VE-Day, and the fighting in Europe is over. The look on Nixon's face is halfway between poleaxed and bursting into tears of joy.
Janovic and the German guard at the checkpoint. After months of fighting the Nazi army, it was nice to see two soldiers who until recently had been trying to kill each other exchanging jokes and stories. At least until Janovic dies in a car crash.
The scene in "Crossroads" where Sgt. Alley gets hurt, and Lipton goes into Team Mom mode and immediately starts soothing him and calming him down.
After Moose takes over command of Easy, Winters can't stop himself from staying up worrying about the men on their first mission since D-Day without him fighting alongside them.
The series doesn't state it outright, but the reason that Winters and Moose were at the checkpoint when Moose got shot was because Winters was wanting to check on his old unit and talked Moose into going out to 'inspect' the sentries. The man had a deep, lifelong attachment to his men.
Shifty Powers, a Toccoa man with fewer points than many of the replacements, laments that he has no chance of going home before the big jump into Japan. His buddies proceed to rig a drawing to ensure that he is chosen 'at random' to go home free and clear. Yes, he was seriously injured, robbed, and got home after most of his buddies due to a vehicle accident, but its the thought that counts.
At the end of the series; The German generals' speech showing not all Germans were evil.
"Men, it's been a long war, it's been a tough war. You've fought bravely, proudly for your country. You're a special group. You've found in one another a bond, that exists only in combat, among brothers. You've shared foxholes, held each other in dire moments. You've seen death and suffered together. I'm proud to have served with each and every one of you. You all deserve long and happy lives in peace."
Speirs informing Lipton that all of Easy Company has considered him their real leader for some time now, as he was just naturally doing everything a good leader should, without thinking about it.
Plus the fact that Lipton was at a complete loss to understand what Speirs was talking about until it was explained to him, point by point. Lipton wasn't concerned about accolades, fame, or reward; all he cared about was his men, and keeping them not only alive, but taken care of.
The entire tenth episode is so heart-warming it could probably replace central heating altogether. The 'lottery' with only Shifty Powers' lot in the helmet? The German General's speech to his soldiers? The baseball game at the end, where the futures of each surviving Company member are summarised? George Luz's funeral?
Winters: You're a hell of a fine soldier, Shifty. What more is there to say?