I would do as much research as you can before deciding on which kit and from where you intend to purchase. I would also recommend seeing if there's a local homebrewing supply store somewhere near you. It took me a couple weeks, and I had resigned myself to buying online, before I found there was in fact a local store. I believe that the option of buying locally, at least some stuff anyways, is getting in good with someone you might need in the future. You never know when you might need something in a hurry, it's close to quitttin' time, and the guy at your local store offers to stay open for an extra 30 minutes so you can come in and get the right sized rubber stopper for a buck.
Barring that, I would have to say that there are a number of reputable online suppliers. One that springs to mind right away is Austin Homebrewing, as they have a representative, here on the forum, and that should carry some weight. Next I'd say Midwest or Northern homebrew suppliers, and I'm sure there'll be plenty of recommendations to follow mine.
I went with a locally bought Brewer's Best basic kit and added a carboy. You'll get tons of advice on which way to go with kits, and it's going to come down to what you can afford, and what your brewing expectations are.
Let the forum know where you're locate and what you'd like to brew and I'll bet you'll get tons of info.