Which forum software is better to use?

It's depend your size of forums.. also cost..

for free, I like phpbb and mybb and for paid one, recommend vbulletin.. We also use vbulletin for our company forum.

thanks

For free PunBB is pretty good.

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"Opportunity is missed by most people because it comes dressed in overalls and looks like work."
--Thomas Alva Edison
"Those who would give up essential liberty to purchase a little temporary safety, deserve neither liberty nor safety."
--Benjamin Franklin
"A happy person is not a person in a certain set of circumstances, but rather a person with a certain set of attitudes."
--Hugh Downs

I like SMF. As for me it looks like vBulletin and at the same time it is free.