If you're interested in a shiny new iPhone 4S, wait until after October 4.
HTC's latest version of Sense for Android is amazing - this latest interpretation of Android very pretty...it's simply beautiful. A mate of mine got a new HTC Sensation - even as a loyal iPhone user, I was very jealous. The current HTC offerings are all outstanding.
I've heard nothing but positive things about the Samsung Galaxy SII. Another friend has one, and it appears to be quite a solid phone. From personal preference though, I just feel it offers nothing better than what HTC can offer.
Don't bother with anything other than these 3 brands...LG, BlackBerry Huawei and Sony Ericsson just cannot compete. And in terms of operating systems, RIM and Windows7 just aren't as flexible or intuitive - stick with iOS or Android.