Consider the Minimig pretty much an A500 replacement with a somewhat higher performance (the 68000 on it can be clocked higher, but it's hamstrung by the rest of the system similarly to how a real A500 would be if you) and up to 4MB RAM (shared with the kickstart).
The FPGA Arcade is AGA (plus possibly some extra stuff), has more memory, you will be able to get a daughterboard with a 68060 + ethernet, and the core it comes with (if you don't use the daughterboard 68060) performs like a high end 68030 / low end 68040 at the moment unless they've managed to boost it even more.
I'd wait for the FPGA Arcade at this point for your purposes (with or without the daughterboard). The first run of boards will possibly/likely be available in November (though likely all spoken for). The second run is of ca. 500 boards.