The pi is wonderful for tinkering. But i'm finding it too slow to do most things I want it to do. The beaglebone black is good but I just hate the micro hdmi port.. I wish they put a reg HDMI port on it.
I've had fun running a Terraria server for 2 people on it. TShock server via Mono and some optimizations and overclocking. Runs fairly well to be honest but looking beyond that I agree it is just too slow to do most things I want to do.
I have a U2 (basically the same as the U3 with less ports), and the thing is so good I used it as a desktop for a couple of weeks (http://the.taoofmac.com/space/blog/2013/02/10/1230) - running NetBeans at a fair clip, to boot. The only thing stopping me from getting a couple of U3s is lack of cash, and I heartily recommend it.
The Pi is... Sort of mediocre as a desktop (even as a thin client) and too complex for most hardware projects. We ran a number of them as digital signage clients for a while (https://github.com/sapo/digital-signage-client) and eventually moved to Android boxes (https://github.com/sapo/android-signage-client) because even with the recent improvements to WebKit and X the browser simply wasn't up to par.
Worked reasonably nicely with videos, but I keep wondering how much more useful the Pi would have been (for signage, mind you) if they had released their internal Android build.
Edit: forgot to mention I have five Model Bs in a cluster (http://github.com/rcarmo/raspi-cluster) where I run distcc and toy with Java/Clojure/Hazelcast. It's fun, but requires a fair bit of patience.
Careful -- That's 65 without the necessary eMMC you must buy to boot it. Makes it at least $80 + shipping for the small 8GB eMMC module.
These things look nice, but I've read some stories about being difficult to get a custom distro to boot (ie. one other than the default distro downloadable on their site.). If the default spin of ubuntu is good enough for you, that's great, but you probably wont get fedora arm booting or anything.
Wandboard is nice -- quad core, 2gb ddr3, 2 mSD slots, SATA, etc. It's a bit more expensive, but from what I've seen creeping the hardware forums, it has better compatibility.
There are a few with quad-core. And added benefits like SATA2 connectors and NEON instruction set on the CPU. Granted that only helps if you compile against it (not likely going to help regular daily use), but if you're developing code on a small device, the gains can be huge.
Dual core Cubietruck (Cubieboard3) is a good alternative (cons: pins are 'non-standard', i.e. they are placed too close to each other).
But quad core (US made) UDOO is better choice for you, if you are in US, since you'll pay less for shipping. Plus, it has Arduino on board.(cons: 1gb RAM, no VGA output).
Both models sport reg size HDMI ports and both .
Udoo isn't bad, except the creators seem to be far better at making hardware than maintaining a linux distro. I've been banging my head into a wall trying to get a non .deb based disto booting. Their kernels are stuck on 3.10.x and are not even current 3.10.x, they're over 6 months without any changes by the Udoo team. Their U-boot is very old as well and has been pretty customized, but the way they do their git repos makes it difficult to determine what commit they started with and what they have modified (they didn't fork the repo, they started fresh with an "initial upload" of a finished and working u-boot for their custom ubuntu image).
Anyways -- I'm looking into checking out Wandboard now, as it seems most of the distros that have ARM releases now cover this board natively (no hackery required).
I have a model B+ and I find it somewhat slow even when just using it as a media player, the audio out from HDMI is also much worse than the 3.5mm. For $35 it's a great deal but i'd much rather a ~$50 price point with more RAM and a faster CPU, possibly onboard wifi as well.
I've had my eye on something along the lines of: http://www.hardkernel.com/main/products/prdt_info.php?g_code...
Quadcore, 2gb of RAM for 65, seems like a nice step up from the Pi.