I am interested in starting some development with the .NET compact framework.
What hardware devices would you recommend for all around testing?
I would like to get two devices, one that has a lot of features and another that is representative of the average device.
Unrelated to the main hardware, but still very relevant, is a good collection of different storage cards/devices of different speeds. For example if your development board has an SD card slot then make sure you've got SD cards in a variety of speeds and performance ratings. It can make a big difference in performance :)
I would suggest two devices: HTC Touch PRO, and a Motorola Q. The HTC Touch Pro has all the mobile device functionality you might be looking for (touch screen, gps, hardware keyboard, and wi-fi). The Motorola Q is just the opposite (no touch screen, no gps [depending on the model]). Also with the HTC Touch PRO, there are communities that can help you with installing new version of windows mobile onto the device. Two that come to mind are PPC Geeks (www.ppcgeeks.com) and XDA (xda-developers.com).
I believe Motorola Q has the same type of communities, but I do not have those links. These two devices you will be able to began your windows mobile development on.
We can't really give you a definitive answer here. The Compact Framework runs on a whole lot of hardware. As a prime example, I work on CF apps on a nearly daily basis, and I rarely use a Windows Mobile device. In fact I just installed the WinMo 6.x SDK on my laptop, and I've been using it for development for probably 3 years. There simply is no "average" device.
The question you have to ask yourself is "what is a representative example of the type of device I plan on targeting?"
If you're going to target PDAs/phones, then I'd probably get a WinMo 5.0 phone for general usage since there is a large install base and 5.0 apps will run under 6.x.
If you plan on targeting embedded devices a good general-purpose CEPC like an eBox 3300 is nice because it comes already booting to Windows CE.
If you plan on using I/O, then you really need to look at a device that is much closer to the actual hardware you would target. In fact, you'd probably want it to be built on your target BSP, since I/O is very processor, and often OEM dependent.