Okay, I first posted this in "A/A subtle acting HOF" thread but then I realized my choices weren't so subtle
so here I am reposting it here:
Willow's outburst on Buffy in Tough Love
Willow: This is not your choice, it's mine!
Buffy: This is not the time.
Willow: When Buffy? When is? When you feel like it? When it's someone you love as much as I love Tara? When it's Dawn is that it?
And also from Tough Love (my favorite) Willow's little outburst on Giles.
Willow: I had a fight with Tara, it was awful...
Giles: Oh I'm sorry. You two don't quarrel much do you?
Willow: Never.. 'till today...
Giles: Oh well it's over.
Willow: Over!? How can it be over? I-I-I've just found her!
Giles: The quarel is over.
Willow: Oh...
Oh, and also Willow's first outburst in second season's Reptile Boy (on Angel and Giles).
Angel: Did she have a date?
Willow: Well! Well, why do you think she went to that party?! 'Cause you gave her the brush off! And you never let her do anything except work and patrol! I know she's the chosen one, but you're killing her with the pressure! She's sixteen going on forty! And you! You're gonna live forever and you don't have time for a cup of coffe??? (then) Okay, I don't feel any better now and we still gotta find Buffy.
Mmmmmmm feisty Willow mmmmmmmmmmm... 
And as for Tara, hmmmmmm, that's a hard choice!
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