Definitely either the G-1 or the iPhone. For email on the G-1, since you have background processes, a little icon appears in the screen when you get new email

Definitely either the G-1 or the iPhone. For email on the G-1, since you have background processes, a little icon appears in the screen when you get new email or instant messages, and you can swipe it down, switch applications to chat for a bit, and then hit the "back" button to switch applications back to what you were doing. So it really makes it possible to do something else with your phone while you are carrying on an email or IM conversation. Same goes for calendar notifications. For this sort of thing I think the iPhone's one-button, one-task-at-a-time interface really hurts. For general applications the iPhone is much better - there aren't that many applications in the G1 market yet. In general the larger screen and pinch gestures make it easier to use the web and maps on an iPhone. For general operating system, I'm torn, because I like the extra buttons on the G1 (notably "back", "home", and "contacts" versus the iphone only having "home") so you can be doing something, send off an email, then resume what you were doing. But the UI is more intuitive on the iPhone, there are many little fluidly animated bits. Hard to say... I have a G1, have used many friends' iPhones, and am tempted to get an iPod Touch so I can fool around with both of them.