Brandmuscle is very easy to use, has great customer service, and they are always willing to help you out! I have been using them for over 5 years now, and they never fail to exceed my expectations. They have helped us with our PPC campaigns, SEO, and email marketing. Their customer service is excellent, and they are always willing to go above and beyond to help you get what you need.
They don't offer as much in terms of analytics reporting, but that's not really something I've needed from them.