Sucks that I can only vote once. The original concept of Bluffside was mine (which existed as a city stat block in an unfinished module), and I wrote probably 80% of the Artificer's Handbook (though, I can not take credit for the actual spell slot mechanic itself, that goes to Manus Smith).
So, you can see that I would be a bit torn between the two.
All these votes in support of both products really warms my heart. I would love to see both an expanded Bluffside product, and a revised/expanded Artificer's Handbook.
On a related note, the errata for Artificer's should be out soon. I just turned the documents over to our layout person a few minutes ago.
Interesting trivia tidbit:
When I started working with Thunderhead Games, I began working on a module that involved PCs traveling a goblin-infested path via a caravan between two cities. So, I needed some cities. I asked Hal, "I need some cities." Hal: "Make some up." Ok, so I created Perten as a starting point. It was designed to be a melting pot city so that all kinds of humanoid races could have some viable reason to be there. There were going to be gnomes in the mountains nearby, and halflings and elves in the forests, etc., etc. Then, I needed a destination. I admit that I really liked the idea from a game I'd been reading about called Horizons, that was a city of vampires called Cliffside. I changed the name to Bluffside. The original makeup was that it was a haven for thieves and mages (an odd combination, yes). It was also supposed to have a rich merchant class. The original design also called for a wall of catwalks and elevators that would haul goods from the sea floor up the side of scaffolding along the cliff-face to the city itself. That eventually got replaced with the underground areas, and we tied in the whole archaeological aspect to it, which I think was a nice touch.
Anyway. Some interesting side information if anyone cares.
BTW, that module never saw the light of day (nor was it completed), but the goblin fortress that was featured in it (Targ Ak'ala Beng) was published in ENWorld Journal #1.