SEO Power Shield Or RYS Drive Stacks

In episode 290 of Semantic Mastery's weekly Hump Day Hangouts, one participant asked which is better: SEO power shield or RYS drive stack.
The exact question was:
To add to my other question should I buy multiple SEO Power Shield or RYS Drive Stacks. I'm excited I just want to make sure my client and I for upcoming cost.
