If all you want is USB, there are (seemingly hundreds of) Allwinner sticks available via Aliexpress, e.g. http://goo.gl/th1bO as low as $34, which is supported via the linux-sunxi port. Boards generally cost more, I've less information on that.
Price
Performance
Exposed I/O
Device Size
Community Size
I don't know of any board that beats the Pi on more than 3 of these attributes.
The allwinner sticks you mentioned are comparably priced, but have a smaller development community and very limited I/O. If all you want is a little media player, I think they are a good choice though.
http://liliputing.com/2012/07/allwinner-pledges-support-for-...
As for lower level development, you are probably right, few boards can claim to beat the Pi.