Ben,
There's quite a few to try. With kits, what you want to look for are buying them from a shop with a good turnover rate. Bigger beer supply stores do more business on volume, which means they sell more kits to homebrewers. Companies like Williams Brewing, Midwest, Northern Brewer, Rebel Brewing, Austin Homebrew and others have quite a bit of turnover. That means fresher ingredients go into the kits and better tasting beer in the finished product.
Kits are step-by-step and generally fairly easy to execute and have a wide margin of error for beginners through advanced homebrewers. They are a great entrance into the hobby for novice brewers and a convenient time saver for advanced brewers. The only major concerns that I have with kits are as follows:
Limited shelf life: Kits usually contain extracts (dried or liquid) and some contain pre-crushed grains for either roasted grain soaking or partial mashing. Kits also usually contain yeast (dried or liquid) as well as pellet hops. All of these ingredients have a limited shelf life and are best used as fresh as possible. I'd recommend not selecting kits from smaller homebrew stores because who knows how long they've been collecting dust on the shelf.