Depends what you want, my employer has foolishly entrusted me with both a Palm M505 (up to 2 weeks battery life) and a nice slim Dell Laptop (2 1/2 hrs battery life).
The Palm is great as a Filofax replacement (Calendar/Diary) and for reading downloaded newspapers (AvantGo) in the bog! You can get lots of apps to add to the handhelds too though. The Pocket PC series (Compaq iPpaq - HP Jornada) offer more in the way of cut down Officy type applications but no matter which type you try the stylus is not a substitute for a keyboard. You can get small fold up keyboards but then (I think) you're starting to get into the silly league.
The laptop allows me to do anything I can do with my desktop PC and (the slim Dell) is not a pain to carry around, unlike some earlier versions I have had.
If you want a glorified diary with some neat tricks go for the handheld, if you want to be able to type an e-mail, document, presentation or spreadsheet then it has to be the laptop.