It really depends on what you want:
Do you want to spend under $200?
Checkout used and discounted Casios (EM500, 115, 125) The EM500 is physically smaller but only has 16MB's of ram (you can plug in MMC/SD cards to expand its external memory though). The 115 and 125 come with 32MB and also are expandable. The 16MBs is real tight on the EM500.
Will it be used outside?
The Casios have a screen that is really only useable indoors. All the PPC 2002 devices have a screen that can be seen indoors/outdoors and they use a lighted screen to achive that. (ie it is lit from the sides so it can be seen indoors, outside it uses ambient light) The downside is the screens dont look as nice indoors as a older Casio. Personal preference and a needs issue.
Is it mostly for gaming?
Look for a device with a nice button layout. All the newer PPC2002 devices have the control button in the center of the unit. This may or may not be a factor if you like how it feels. Again the older Casios have the controller on the left side like a Gameboy.
Deciding between a PPC and a PPC2002 device:
The Pocket PC 2002 units are all very similar and all run the same processor (ARM), Software is slowly being phased out for the older processors (MIPS:Casio and SH:HP), as time goes by more and more stuff will be ARM only.
If your willing to spend $350 the Toshiba E310 is the cheapest (I think) PPC2002 model. I dont know any specifics on it (again the PPC2002s are all very similar in specs) or if it has any pros/cons as far as gaming goes. There are plenty of PPC websites with this kind of info www.pocketgamer.org is one where you could post any questions realated to games and a specific device.
I have the EM500 with a 64 meg MMC card and it runs everything pretty good, but I am sure the new faster units would make mine seem slow.
I guess it boils down to how much you want to spend, but there are many who were disappointed in that fact that all the new PPC2002's have the same button layout (centered) and all have the indoor/outdoor screens and these people are sticking with the old Casios rather than upgrading.