Considering that with the ARM board, I believe the 68000 can be clocked in excess of 40MHz (although I think the non-ARM version can get to 28MHz), you do get a very fast "basic" Amiga out of the box. Faster than a stock A1200 in terms of CPU power, albeit with OCS, not AGA.
FPGAArcade is the next generation of classic Amiga implementation, doing AGA.
Beyond that is Natami, but they keep on expanding their scope and getting lost in their "68050" CPU they're designing, although it should end up being a good core. Natami will require a more expensive board due to needing a bigger FPGA. It'll be what a classic Amiga would have been in around 1997 had development continued (and the 68000 series had stayed the CPU of choice).
Personally I'd love to do some Blitz Basic development on a Minimig (although I'm waiting for FPGAArcade), or create a cross between dungeon keeper and Doom.