There are plenty of people that brew award winning beer with extract as well as all grain. It really comes down to what you are comfortable with and how well you understand the process of brewing. In addition, as with anything, the freshness of your ingredients. If you use fresh extract vs old grain, chances are your extract batch will be better, all else being equal.
Extract is more expensive per batch than all gran but all grain brewing requires a larger initial investment in equipment. All grain is also a more complex brewing process with a lot more variables involved in refining your process, understanding the mash, using water, etc.
All Grain brewing allows you full control over each ingredient and element of your process but also requires a greater understanding of how each affects your beer so there is a much larger learning curve as well.
Time is the last consideration, extract brewing is less time consuming to create the wort. All grain brewing for a 5 gallon batch generally takes me 5-6 hours from set up to cleanup and pitching the yeast.
If you want to make the jump I would highly recommend reading John Palmer's "How to Brew" There is a free online version but the latest purchased edition is much more updated and current.