I have never used the Filco, but I have heard great things.
I do have a KUL, and as my first mechanical keyboard, I have no regrets. The only thing that I wasn't thrilled with was the ABS keycaps that came with it, they just didn't feel great. I really felt this lack of quality when I bought a custom set from WASD, which are also ABS. I am not sure how others regard the WASD keycaps, but they feel miles better than the stock ones. I didn't really care about the stock caps when I bought the KUL because I knew that I would be changing them out.
I've had the KUL for about four months now and I enjoy it as much today as I did the day I got it. I love the flexibility and build quality of it. If I had to make the purchase again, I would in a heartbeat.