Good thread ... I'm going through the same question -
Although now Air Nav Pro have launched their excellent Nav software for Android it still seems like its not as good as the Ipad version.
I am a real Android fan (Galaxy SII phone) and really hate the Apple philosophy BUT I think they have got it right with the Ipad .... so many dedicated Apps written for it, especially for GA ... and additionally things like cockpit mounts and covers are freely available for the Ipad ...
The other consideration is that the Ipad 3 has much better resolution, its significantly better than the Ipad 2 and Tab 10.1's screen especially when viewing sectional charts on it .....
I hate the fact I HAVE to buy the Ipad 3G(4G) version to get the GPS built in .... BUT I am very very close to buying one now!!!