[vettestr]

A wiring harness is a fear of many new builders. It is more of the unknown that is a little intimidating. As a Kit manufacturer we have been through several sources to find the best documentation available. Most of them have had good to high quality wire/components making up their kit but STINK on their documentation. All of the wires had good labels and numbers but the charts and even colors on the doc package were wrong on most. A 12 circuit kit can only be so tough if taken 1 circuit at a time with or without the supplied documents. If you understand how each circuit works you can make your own diagrams as you go.
We found a manufacturer that had a very good wiring kit but terrible instructions. ... isn't this special ! We documented each circuit ourselves with wire length and all to each component but this is a fair amount of work the first time for sure. The purchase price was lower than others but once documented we were good to go.
I have not seen the kit from Finishline or Ron Francis myself but Finishline has always been upfront and honest with us. Call them and ask about ease to install their kit. As far as best documented kit I have seen the Painless is about the best, but they are also more expensive. If you are good with wiring then most kits have basic quality needed but be ready to ring out each circuit yourself on less expensive kits.