I have been a huge fan of the classic Auctioneer since I started playing the game back in the beginning stages of TBC, and it worked for me all the way until patch 4.0.1, Destroyer of Addons. With Auctioneer out of commission during that Black Tuesday, I decided to give Autionator a try. And I have never really looked back.
What is the difference? Auctionator is designed to be easy to use. Drag and drop your items into the box (or Alt-Left Click) and it will automatically undercut the lowest auction, with your competition listed to the right. If the lowest is too low, just click on what price you want to undercut. Hell, you can even buy other peoples' auctions or cancel your undercut ones from this same screen. Auctioneer is capable of auto-undercutting, but you actually have to hit Refresh to get the current prices, which doubles the clicks necessary to offload your loot.
The Buy tab is similarly elegant in its simplicity and power. Want to see the current prices of Amberjewel and what it can be cut into? Bam! If you have auctions up that are being undercut you will see a red X next to it, compared with a green check-mark to show you are still the classiest act in town. Your most recent searches are saved along the left-hand side, but you can make shopping lists if you want to be pro. One of my favorite uses for these shopping lists is using the "advanced" search function which looks like this:
This search string will bring up every scroll for that gear slot and clicking the price will re-sort them so the most expensive (and thus most profitable!) are at the top. You can do the same thing with Glyphs if you want to remind yourself how much you hate the Blizzard designers.
I am known to troll the AH for deals on occasion though, and unfortunately Auctinator does nothing to change the hideousness of the default AH screen. That is why I do recommend installing Auctioneer too so you can easily browse 50 items at a time and sort things by prices. As has been reported on some of the other blog sites though, the future of Auctioneer is currently unknown considering the sweeping behind-the-scenes code changes that make scanning the entire AH in a few minutes unreliable at best, impossible at worst. While I recommend using Aunctionator simply because it IS a good AH tool even compared to Aunctioneer, you may want to become familiar with it should Auctioneer suddenly find itself no longer working or being discontinued.