Im a fan of the Android OS that runs on these phones keith
v2.1 is sooo much better and the improved hardware of the newer phones means it runs swiftly.
v2.2 is imment to be rolled out too, the pace at which updates are coming is pretty mindblowing.
HTC add their own customisations (called SensUI) on top of 'vanilla' android, a lot of people prefer the way it looks/acts.
the downside so far is that updates can be slower (as HTC have to wait for the update then add SenseUI back on top) , but the 'fragmentation' of the android versions/platform is being addressed
Current top of the crop are
Motorola Droid , really kick started the android 2.0 phenomenon but getting old now
Google Nexus One v2.1 but will get updates first as its 'Googles' phone.
HTC Desire : v2.1 +Sense
(the two above as Ive said are basically the same phone)
HTC Incredible is the new king.
I used to love my N95 , jumped to v1.5 android (a tad too soon) , but love it and desp want a NexusOne/Desire
Its also worth mentioning that Nokia are making good improvements with their new 'v3' symbian OS
just dont expect anything like decent battery life if you use all its functionality.
also google maps nav is now enabled for the UK (free satnav)