Word on the street is production is stopping on the galaxy S (super amoled capacity issues) so they’ll be hard to get soon.
Despite the occasional lag and GPS issues the galaxy is probably the best of those three android phones. Desire would be better if it wasn’t for the screen (gash outdoors).
I’ve an X10, which given how much you can customise android (and most reviews you’ll find are of it stock on early firmware) is decent, with a great screen. None of these will have the battery life you’re used to with the E71.
However, the X10’s been sat gathering dust the last two weeks since I got an N8. I could write a lot about it, but instead I’ll direct you to the various articles over on http://thehandheldblog.com/ basically the more I use it the more I like it, it’s a lot better than previous symbian touch phones.
(edit vivaz completely different to an X10, the vivaz is fairly well recognised as an abortion of a symbian phone)