I bought all of my equipment last year (with exception to tanks) and I spent the year before that obsessing about what gear I was going to get while I saved the cash to get it. I was reading tons of ratings in magazines and online and settled on a few key items:
1) Zeagle Envoy Deluxe Regulator (the Deluxe is nice cause it has a lever for controlling your air flow at second stage)—mid-priced with great ratings
2) Sherwood Wisdom dive computer: I agree with Punk about the computer...it makes the dive controlled and more enjoyable--whether you're diving a wreck at 130 feet or 50 feet—this one’s considered by most to be top-notch
3) Oceanic Probe BC: BCs don't matter too much to me...they all pretty much inflate and deflate—but this one’s highly rated, versatile and affordable
4) Oceanic Spinner knife: Just kidding. I love those divers on the boat who think they're gonna take out a Great White with the 12" Bowie attached to their calf. It must make them feel like Commando or something.
All of the above, with exception of the indispensable submersible knife, are top-rated for serious sport divers.
Now the best part: All the equipment I got retails at over $2k. I got it all new with warranty on eBay for about $1,200. If you do this, avoid telling your local dive shop about it if you want to maintain a cordial relationship.