i want to know what is the best brush smoothing for animating ?

100 or 0.

It's all down to preference. Usually it's 25-50 for most people here. Experiment with them and see what you like.

At the beginning I used to use 25 because it always appeared smoother to me but that was not the case. Now I go between 0 -10

If you use mouse then 30 would be good enough I think.

Or 100.

Personally, I use 20, it gives a decent line, it doesn't change too much after you've drawn it, or like smile said, 100 would do. But just experiment with different ones until you find the one you like the best.

I have to say it depends. But it would range above 10-15, and below 50.

And so this becomes the next Chat thread
ANyway I agree with most of the others that below 50 is best.
Of course have it around 20, not a have to to have it at 20.

Like Rosie and everyone else who said it first, it all comes down to personal preference. I typically use 40 smoothing, while I've seen some animators around here's brush smoothing nearing towards 0.

Never use 100 unless you'd like a challenge, lol.

thanks guys for the suggestion :)
i think i'll use 30 after experimenting 0-50 :D