I can't actually recommend a particular device, as I use an Axim X51
v which Dell have decided to cease manufacturing (big shame, as this is a lovely device to use).
So instead, here are a few things that you should consider....
Styling
There's three main styles, Folding, Tablet and Sliding.
Memory
Onboard memory and then SD/CF options.
Connectivity
Most devices have Infa-red and Bluetooth, but do you need buit-in wireless or GPS?
Operating system
Presumably you will be looking at Windows Mobile 5 or 6 if your wanting to run B4PPC.
Price
Probably the biggest decision is how much are you willing to pay, devices can range from £100 to +£500
I also wouldn't rule out a smart phone, OK the screen is smaller but then you've got a PDA, camera and ...uhm oh yes a phone crammed in there. My friend has an MDA Vario, now that is a nice unit!!
Anway, here's a couple of informative links for you to check out if you want to know more...
http://www.micromart.co.uk/features/article/default.aspx?id=22289
http://www.micromart.co.uk/features/article/default.aspx?id=21722
Regards,
RandomCoder.