Frameworks are very useful for MVPs. That said, this subject has been debated endlessly here on FD. My recommendation is, if you can go native. On the long run is better. Xamarin is very good, you'll be married to it, trying to find someone who know Xamarin whenever you need to upgrade your project. This last tasks it's not impossible, but the amount of Xamarin developers are certainly less than native ones. Resources availability matters.
METOR: Avoid it. Incomplete IDE not even capable of compiling its example app on the phone device. In my case it didn't even find the phone device to push for the app. In theory METEOR sounds nice, in practice it's incomplete, to put it nicely. Because METEOR is a much smaller community, in case of problems, you'll find far less solutions, furthering up the degrading cycle. I really tried with METEOR and tried to give it an opportunity, but no, we just couldn't made it work, something that in other IDE's was a piece of cake.
Best of lucks!