Which law firm to use for EB1A

I am an engineering manager at FAANG and have an industry profile. No academic profile like publications or papers. I was thinking of choosing between -

1. Manifest Law - Gold package of 60% money back guarantee
2. Stelmakh & Associates

I will have to build a little on my existing profile before filing. Folks who have gone through this, can you recommend one of the above 2 firms and why?