eibach vs roush vs ford suspension

Good night, how do you figure which one to use? I was going to install ford after watching motorz do it, I liked what I heard about roush and now I saw an episode of motors that installed an eibach suspension.
I am starting to get into auto cross, and I wanted to change my car. How does one decide on which company to go with? I noticed that many of you have mixed and matched set ups, but I have also read to go with one company as they are designed to work together.
Any help? I have an 06 gt, which for now is stock.
Thanks,
Doc

Thanks for your input guys. I am looking into all of this. I am having a hard time finding the rules of autocross and where changes will place me. I really want to supercharge my car, the roush suspension is supposed to be tuned for the wt of the roush, I will lean there.
I have been impressed with the adjustable suspension systems I have seen, I will look into those as well. I have been waiting to get into autocross and mod my car, life keeps getting in the way! My kids are starting karting, so the money might go there as well as my time.
Do you guys have any autocross sites you would recommend? I will keep you posted on my goings on here. My wife had put some money aside for my supercharger, then found out I needed 2k more for the one I wanted! I then found something I wanted for my office to spend the money on. I liked the old days when I would spend my money without regard, now with kids....well they are the true treasures!
Thanks guys, sorry for the ramble,
Doc