What Sequence for Listing Forum Posts

I have several choices for the order in which forum posts appear on the front page. I'm having trouble choosing between two defaults. Please give me your opinion on this:

Default 1: Would have the post that has most recently have activity on it be listed first, then the next, ad infinitum.

Default 2: Would have the post that was most recently begun first, then the next, ad infinitum.

Default 1 shows you quickest where the commenting activity is. But it also can mean that a new post that is not quickly commented on can disappear from the front page.

Thoughts?

[Bryce @ Treebangers Disc Golf]

Default 1, thats where the action is!