One more link to what HubSpot thinks about WordPress versus them:
https://www.youtube.com/watch?v=lHa7xjzSLh0
I have summarized some of the plugins they mentioned in the video below categorizing them via a standard sales flow for inbound marketing (create, optimize, promote, convert, analyze). Assuming you implement good plugins (maybe those below? Others?) and use them well, then what value do you see in Hubspot?
Create
* No plugins needed. WordPress is enough.
Optimization (SEO & Keyword Testing)
* All in One SEO Pack (plugin for SEO)
* Yoast SEO (plugin for SEO and keyword testing)
* Google Keyword Tool (not plugin, but easy to find testing tool)
* HubSpot (paid keyword testing tool)
* SEO Raven (paid keyword testing tool)
Promote (mainly social media)
* ShareThis
* Shareaholic
* WP Socializer
* Network Publisher
* Tweet Old Posts
Convert (ie, Landing Pages)
* Wufoo
* Contact Form 7
* Hubspot (paid)
* Premise
* Gravity
* Optimized Press
Analyze (& Conversion)
* Google Analytics (plugin)
* CRM (Sugar, SalesForce, etc)