End of Torchwood would make me cry, mainly because there is no WAY they'll finish it satisfactorily. We will never know what the deal with Janto is. We will always be left with the nasty feeling that Gwack might not be a figment of our imaginations (or even, we'll have it CONFIRMED in the LAST EVER EPISODE, damn).

I don't want Jack to leave - I don't think Torchwood would work without him, despite my opinions on Harkness-as-lead-character. More Captain John would be excellent, but again I think he's the same sort of wouldn't-work-as-a-main-role part.