I'm not one for comparing products which don't exist yet to products which are already on the market, but James Kendrick has written what I think are a good set of reasons why he'll be first in line for a 7in iPad, despite liking the Nexus 7:
Using an iPad is so much more pleasant compared to the Nexus 7 that I am confident that the rumored iPad Mini (or as I prefer to call it the iBook) will capture the small tablet market and quickly. The pricing Apple puts on the smaller tablet will certainly be a factor, but knowing the company I believe they will get it right.
James is right. I own both the N7 and the latest iPad, and while I like both a lot there's a big difference between the two in terms of experience. Even though the N7 is much smoother than previous Android devices (thanks to Jelly Bean) it's still not as responsive as the iPad.
More importantly Android's still lacking in quality applications built for tablet sized screens. There's still no killer Twitter client, although a couple come close. There's a few decent games, but not many. There's no writing app as good as Pages, or presentation app as good as Keynote. Android has occasional quality tablet apps; iOS has depth in quality.