Just like a relationship, work-life rarely achieves a 50-50 balance.
Today's career is about finding the perfect "fit" that is:
1) an extension of who you are
2) passion + strengths + experience
Life is a mixture of different categories, but primarily relationships. The challenge is not necessarily balancing the two, but prioritizing. For example, if you are career driven, you might put your social life on hold because you love to achieve. On the other hand, if relationships are what you're all about, your work may not be as important. There are points where perfect harmony can be attained, but it's very rare.
The point is: you have to choose which one comes first.
I can't tell you which one is "better," but I can share from my own experiences. I value relationships. My wife, family and friends come first. That doesn't mean I don't care about my career, because I do, but if I have to choose, it's my relationships. I have my own business, helping people identify and grow within their careers, but my primary motivation is the flexibility of schedule. Controlling how I spend my time means I can work my schedule around my wife's. Even the network group I created, Career Synergy, is relationships first, business second. I truly believe that your strongest career asset is your personal network - the people you know.
So can you achieve work-life balance? The short answer is yes. The better question is: What's more important? It's said if you want to know your priorities, look at how you spend your time and money. Instead of trying to be a master of juggling, figure out the order of importance.