Disclaimer: I work for a Pardot services firm. We don't sell the software, but we benefit from customers hiring us to help them with Pardot implementations and on-going campaign development services.
In our experience, it doesn't really matter which of the two (Marketo or Pardot) you choose. Each has their pros and cons. Pardot has fewer features than Marketo, but it is easier to use.
The biggest things you need to consider are 1) your team, and 2) your resources.
1) Your team. While Pardot has an easy-to-use user interface, it does not necessarily mean that it is "easy" to implement all of the amazing automation features. It takes someone who can really understand databases, automation logic, and a really deep understanding HTML/CSS coding. Yes, it comes with out-of-the-box email and landing page templates, but sophisticated companies end up wanting custom templates developed and that is not easy. Warning: running Marketo or Pardot is NOT like running a more basic email program like MailChimp or Constant Contact. You need a "full-stack" digital marketer on your team and they're hard to find.
2) Resources. Everyone always underestimates how much effort it is to implement all their awesome ideas for Marketing Automation. In reality, it requires a full person dedicated to running the software. If that same person also has to run events, social media, tradeshows, etc... they will not have enough time to fully utilize the system and realize the ROI you're expecting out of it.
If you can't afford a full-time person to run the MA system, then you should budget for an outside services firm like Audaxium (shameless plug) to do some of the on-going campaigns and drip program development work.
Let me know if you'd like to have a chat offline. :)