Nice christian values
Instead of multiple independent app stores, why not have a few default ones, and then layer on top 'verified by X' trust lists?
Google can run their own trust lists, other third parties (whom one can subscribe to) have theirs. Then when one searches the store for an app, with one's lists applied, only apps which match a verified-by list are shown. If I trust my fiends Joe Smith's trust list (by subscribing to it), then all the apps he reckons are thumbs up are included.
This way no need to deal with multiple app stores (for the developers and the users), only trust lists. This would make it easier for all. The devs wouldn't have to jump through hoops for each app store, the user wouldn't have to add multiple competing stores with duplicate apps, logins etc, the app store moderators wouldn't get so much flak if they decide an app doesn't cut the mustard this time round (as the app is still available).
There could even be incentives in it for google. Some apps could be marked as thumbs up by an automated system for the 'google default' verified-by list. A 'google premium' list could be maintained for those that go through tighter scrutiny and pass a higher bar, which may incur additional costs to the developer (or a higher percentage cut by google). The converse might be true too. Those who meet the default google trust list are hit with a slightly lower google cut.
Of course third parties could also apply this same mechanism. You might pay to access Joe Smiths verified-by list, as he might spend a long time analysing apps and trying to break them, perform security analysis etc.
If one could then also combine lists, say, it has to pass the google defaults, the premium level, Joe Smiths super secure list, and Mandy's performance and good UI list, plus my friends totally unsucky apps list
I think this could cater to the needs of all. In the case of the 'average' punter, the default google list would be applied.
And throwing in a few buzzwords, like block chain, I could imagine a mechanism through which these trust-lists could be maintained. Developers hash, application hash, app version hash, binary blob hash. The app store proper simply stores the artifact and exposes the metadata.
My 2 cents.