Are you looking for a tool for campaign management for day-to-day? I've used a wide variety of the tools such as Marin, Kenshoo, and Aquiso and I would say Kenshoo does a pretty good job. Marin has to many errors that occur within the UI and it just seems like I've had a lot more issues with it than the other platforms. Kenshoo also has their own offline editor tool which is a big plus. I also believe the Kenshoo algorithm for the bid policies does a better job than Marin. I've noticed much higher CPC's over time within Marin. A cool new bidding tool that is coming out that I want to try is Campanja.
Finite is right, there are many tools that you can use for your PPC campaigns. I will also recommend the Kenshoo algorithm, it's quite good I've been using it for a few months now. If your conversions include calls then have a look at this article http://www.infinity-tracking.com/blog/2014/10/improve-your-ppc-bid-management-and-get-the-edge-on-your-competitors-with-keyword-level-call-tracking/ I found it really helpful, it tells you how to improve your PPC bid management with keyword-level call tracking. I believe that the best way of leveraging PPC is by knowing, which of your keywords perform best.
There are good call tracking services that gives you or rather tells you which of your keywords are doing best in your campaign.