The RK-9000 is also something to consider when thinking about a filco!
It's basically a filco clone for close to half the price, about 90 bucks on newegg. I got mine for 60 during a sale! There are a bunch of places you can go to find the differences, especially on GH. I don't own a filco so I can't comment on long term build quality or anything like that, and I've only had my rosewill for about 8 months so while there aren't any signs of wear or tear, it really hasn't been long enough to judge. But I have used a friend's and I know that the filco has rubberized feet on the risers while the rosewill doesn't, and the rosewill has a fixed usb cable port on the right side while the filco has channels underneath like a QFR where you can make the cable come out of either the center, the right, or the left side of the keyboard.
But the big thing is, if price is an issue, then the rk-9000 plus a set of PBT keycaps or custom ones, will cost you the same as just a filco.
If price isn't of concern... well, then buy both boards and all the keycaps you can!