Which of these content planning tools do you like the most? PageOptimizer Pro - Surfer - Clearscope - ZenBrief - DemandJump - ContentHarmony

Does anyone have experience with the majority of these tools and can you tell me which you like the most? I really want to find a great tool to help with the following...

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• Keyword research (tool that provides primary, secondary, LSI groups)
• Content clusters (I want something to help me define pillar pages and related pages that are like spokes coming out of the pillars)
• Content outline development (I would like to find a tool that helps me create comprehensive briefs)

It seems like most of these tools are pretty similar but the price differences are significant.

I will probably trial a few of them, but I was hoping that someone might have the inside scoop :)