Wood R4 is a modified version of the Acekard Kernel to run on R4, M3 Simply, and R4i Gold (r4ids.cn.) It's basically praised for introducing all of the Acekard features so it basically had almost all the same features as akAIO. The only feature it didn't have was individual loader updates. Otherwise it had basically everything else.
I always suggest it because it's extremely light on the battery, the ROM performance is perfect, the RTS is stable and simple, it's easy and highly customizable, homebrew soft-reset, and so many other features. I personally think it's the best kernel next to akAIO and it's also why I always suggest the R4i Gold over other carts. http://www.nds-card.com/ProShow.asp?ProID=149