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For me it was mainly between the blackberry bold 2/9700 and the desire. The desire really is awesome in terms of what google is doing with apps like sky maps/layar/goggles etc. Also has a million times more apps than blackberry. The email on blackberry works a bit better because it has push mail for pretty much everything whereas desire only has push for gmail and everything else has to be set up to be polled every 5 minutes or so. Also blackberry has BIS unlimited internet so with desire you'd need a data bundle. The SE X10 has a bigger screen but desire has android 2.1 and X10 1.6. Also HTC Sense is pretty good, even people with the google nexus one putting the htc firmware on to get it.