The Palm wins hands down for my purposes(M505).
And it's the only one worth having that fits in a typical shirt pocket. All the others are "nav bag" or "briefcase" jobs which is a huge negative as far as I'm concerned.The trusty Palm goes where you go without having to lug a bag around to carry your not so portable PDA.
I use it in conjunction with a laptop "mothership" to "Hotsync" data etc.
The laptop is also usefull for entering text etc.instead of the graffiti method.
Battery life is also excellent.
<img src="tongue.gif" border="0">