Actually the best value for money is probably one made yourself. The question wasn't about value for money though I think it it was about performance.
I'm afraid I haven't heard either of those against each other. I have heard the signature digital incon and it works. I would suggest that you find someone who can let you borrow them on sale or return. The cables Ian refers to should also be considered even althogh they are much cheaper. In my experience, good Belden RG59 or RG6 spec cable, fitted with crimped on 75 Ohm RCA's or BNC's from a company like Canare should give excellent results. (This is what Mark Grant does I believe)
I think Mark does use the above top quality components, price and service (and customisation to desired length) is excellent, so only his craftsmanship is the remaining factor. The one he made for me looks superb, and I would bet he can outperform any factory for quality control.