Recently I published a android market application, made in construct 2 and built with phonegap. Also some time ago I published here a link to an article about how developers using appmobi should move to phonegap. As now I can take side, I'd like to do it here and encourage other people that have published their apps to market, to do so.
AppMobi has a HUGE problem with published apps. It's not having a control over application version. This means, if you plan to publish an updated version of your app, it will have the same version number on android market. On the other side, in phonegap you specify your app version, which after upload to android market will SEND A MESSAGE to all your app users (that are currently online, because market app needs to check this), that there is an updated version available and that they should download it.
PhoneGap has also a HUGE problem. There's no sound support in construct phonegap builds (currently, I don't know if this is going to change - @Ashley ? :) AppMobi has no problems with sounds.
Couple of minor differences between phonegap and appmobi I encountered:
1) in phonegap you CAN remove the native status bar and launch your app in full screen, in appmobi there's (currently) no option to remove phone's status bar.
2) in phonegap you have more control over permissions your app requires, minimum is storage, calls and network. in appmobi there's reading and writing contact data (exclamation mark here) required.
3) phonegap seems to be easier to build, you upload code to phonegap build and it's done.
4) appmobi builds have a com.company.company.appname package name for some reason (or maybe I didn't configure appmobi correctly)
5) phonegap seems to be actually quicker than appmobi (about 5-10fps more on my nexus one android), but this probably will change when construct will support appmobi's direct canvas.
6) phonegap build service allows only one private app, which is not a big deal for me as it can by any app any time. this means no application management at all, in appmobi you can have as many apps as you please in one time.
In conclusion, if construct team would be so kind and fix sound support in phonegap, I would move (and would recommend all of you the same) to phonegap.
TLDR: Construct team, please fix audio in phonegap, and all of you out there, make your builds with it. in appmobi you don't have control over application version which will prevent you from updating it via android market app.