Hehe. Before I can help someone else, I'll have to make up my own mind first. Love the fact that the Mini now has a Retina display. But I also like how thin and light the new iPad Air is. Looking at videos on the 9.7" screen will definitely be a plus over the smaller screen on the Mini even with its new retina display.
A lot of that has to do with form factor though which we've already had a year to figure out. What's changed? The Mini has a much better screen and on par internals. The ipad 5 is slightly thinner and sheds a .4 lb.
Looking at videos may be better on the ipad Air, but the same thing applied to the ipad 4. I probably wouldn't hold the bigger ipad while watching videos..it gets propped in lap or sits in a stand. Even with the reduced weight, the ipad air will still be too large for gaming (hand held) and still too heavy to hold for a long time.
In terms of usage though, the Mini is more versatile IMO.
The only thing I'm not factoring is the lesser footprint of the ipad Air. So it's not a clear cut answer (as well as the things the Air may have such as more RAM..don't know yet). We'll get to see the Air first definitely though and have time to figure it out. The Mini is probably something you don't have time to see in stores later in Nov. You either preorder or line up, or you might be waiting.