Installing Wiki on Multisite - Better to Active Single-Site or Network-Wide?

I just downloaded Wiki for the first time and want to install it on a site running WordPress Multisite. I only want it enabled on one site within the multisite install (i.e. wiki.domain.com), but I would like it to be accessible/editable by anyone registered on the entire network. Is it better to activate the plugin on a single site or network-wide?