It really depends on what you need the full frame camera to do.
I have owned the 5D, the 5D2 and rented the 5D3. I have used - but never owned - the 7D.
I have owned (and subsequently sold) most of the xxD series.
Since you have the 10-22, a great lens, that's a reason to keep the 7D. I don't know whether your Sigma is a crop only lens but if it is - there's another reason.
There'a rumor of a new Canon full frame - more basic model - coming out this fall. Just a rumor.
If shooting in high ISO and very low light situations is a big deal for you, then I would get the 5D3 and sell whatever you have to get it. It is, IMHO, for that purpose, a game changer. Over both the 7D and the 5D2.
Otherwise, though there are plenty of complaints re the AF ability (or disability) of the 5D2 (certainly not as good in that regard as the 7D), I would say get the 5D2 and enjoy. The 5D2 is still a great camera. Of course, I think the original 5D is still a great camera.
Be aware, however, in some ways (AF for example), the 5D2 may seem like a step backwards from the 7D.
You can't go wrong with any of these cameras.