Depending upon what aspect of AdWords you want to automate, you can look at various tools. As Megumi suggested, Marin is a good option for bid management. You can have a look at Optmyzr (optmyzr.com) to automate account management activities. Cyfe is another option to automate reporting and building dashboards.
I’ve been working with Acquisio for 3+ years and have been really impressed. Their BBM tech has had a significant impact on the performance of our campaigns, we generally see a 40% bump in performance when we take on a pre-existing account and layer on BBM.
I did look at the others but the cost/benefit ratio on Acquisio was strong for our scale (1M-2M annual).