As for fpgaarcade, Im not nearly as informed as some, but I was under the impression it's somewhat more "ambitious" (for lack of a better word) than minimig. Correct me if Im mistaken, but doesnt it support aga, and faster cpus than minimig
You're right, it supports AGA. As it stands, the FPGA Arcade comes with 32MB RAM, I believe, and the CPU performs at the level of a 50MHz 68030, though Yaqube has said he hopes to match a 68040 @ 25MHz in terms of performance. There's also a 68060 card with ethernet (there's a 68060 card for Natami too, but it's mostly for development use and possibly if you need an MMU). The source for the cores is also due to be released, so the community can improve it further.
Natami likely has faster memory, and certainly more, USB, PCI, ethernet and in general lots more expandability out of the box. It of course also has "Super AGA". It also has a bigger/faster (and more expensive) FPGA.
There's a big gap between them, but FPGA Arcade certainly is a massive step up from Minimig. Consider FPGA Arcade a souped up A1200 and Natami a fully decked out A4000 perhaps for a rough idea of where they stand relative to each other. The Natami should in theory at least significantly beat an A4000 with the fastest 68060 accelerators around when using the softcore CPU if it performs as they hope.