I used to have a small 40k Chaos army, but my main army was the Imperial Guard. The fact they were only slightly more advanced than current technology (If you call using laser pointers as guns "more advanced") but most importantly, they were just human (I know, the irony of a furry wanting the human army).
I never liked the Jungle Fighters, so I went with the Cadian option, and this was back when the Cadian's were only available in blister packs. I sold them all a few years back though, when I went to college and it became clear that I wasn't going to have every Thursday night free to conquer the universe in the name of the God Emperor.
I'd possibly like to get a small force of Cadian's again, just as a diorama type thing. I'd probably not game with them, I reckon there's so many new rules and changes since I last rolled a dice I'd be out of my depth.