That all depends on your preference. The Palm OS market is pretty large, and there are many to choose from.
The Windows based PDAs are also popular, and probably more powerful. But again that depends on what you want to do with it, besides geocaching.
If you are going to use it for an appointment calendar, and for paperless geocaching, my suggestion would be to get used one maybe on ebay or an inexpensive Palm based Zire. http://www.palmone.com/us/products/handhelds/zire/
For $79, you will get exactly what you want as described above.
However, if you are really going to get into wireless, and want more of a pocket PC, then take a look at something like an HP iPAQ h1945 Pocket PC http://www.amazon.com/exec/obidos/tg/detail/-/B00009RL1W/002-3280931-8102410?v=glance which is about $300.
I plan on having a paperless geocaching clinic with someothers who use windows based PDAs, as I use Palm OS. Come to that and take a look at what is there. Maybe that will help? See “paperless Geocaching” in this “General” Forum.
[This message has been edited by WISearchers (edited 03-28-2004).]