Thank you all for your comments, they are very interesting and informative, so it is a big help for me.
I think I am going to drop iphone4 off the list because it is on the most expensive plan, a 4 to 6 weeks waiting list, the glass screen and backing is very fragile (people seems to confuse hard scratch resistance with toughness), and the fact that everyone has an iphone. It was a mildly scary experience to be in the train completely surrounded by people using the iphone, ipod and ipad on several occasions, and everyone in my office has one.
Next off the list is the Nokia N8, I played around with it at the shops, it feels nice and solid but I just don't find the user interface attractive, and it seems to be slower to load and browse than other phones.
I was considering the Sony X10 before but after reading your comments I won't.
So now it is down to HTC vs Samsung.
If you're willing to put up with Vodafone as a carrier, the HTC Desire HD or the Samsung Galaxy S are fantastic choices. Both are available on the new Infinite plans, which sound pretty good - $45 p/month for infinite text and calls with 1GB of data, which should be more than enough for the average user.
Of course, if you're willing to pay a bit extra for a much better network in Telstra, they also have the Galaxy S and the HTC Desire. Surprisingly, Telstra seem to be quite competitive with their iPhone 4 plans, to the point where they're more or less the same price as the plans offered by both Optus and Vodafone, but their Android offerings are quite a bit more expensive than their rivals.
I have been with vodafone for the past 2 years, they are average at best, I have had random connection issues from time to time, sms delayed by 5 to 6 hours or more, and no connection for up to 2 weeks, only to read about vodafone's failed network from the newspaper (great customer service there).
Those $45 infinite plan offered by vodafone does not include the monthly payment for the phone, so it isn't as cheap as they make it to be.
Telstra has the best coverage but I am not willing to pay for their prices. After a bit of asking around, the feedback I got is that everyone pretty much hated their network provider, be it Optus, Virgin, 3(now combine with voda). So I might just stick with vodafone again, or join TPG mobile, their plans are dirt cheap, but their service might be worse that the major providers.
I got a feeling our phone deals are no where as competitive as the overseas market.
So what kind of plans are you guys with and how much do you guys have to pay?