right now the fashionable ARM boards are: * panda board (omap4) [1]
* beagle board (omap3) [2]
* trimslice (tegra2) [3]
* arndale & chromebook (exynos5) [4]
* cubieboard (allwinner a10) [5] I've got all of these boards, and I like the pandaboard the most, then the trimslice.
For opensource events the one I use to demo fedora is usually the pandaboard.
That is because Texas Instruments did the best job at upstreaming the kernel code, so it works the best. The cubiboard is nice, it is the same SoC in the mk802 [6]... which is close to the price point of the Raspberry PI except is WAY much more powerful. I guess the question to you is what do you want to do? Do you plan to use any kind of GPIO pins, to say... use LEDs or interface to something else? Or would you be happy with just video output? [1] http://www.omappedia.com/wiki/PandaBoard
[2] http://beagleboard.org/
[3] http://trimslice.com/
[4] http://www.arndaleboard.org/
[5] http://cubieboard.org/
[6] http://www.rikomagic.co.uk/