Dark chocolate started worming its way into my life about a decade ago--not really as a conscious decision ("Hey, I think I'll eat a lot of expensive chocolate!"), but just through gradual upgrades as I became aware of or gained access to better chocolate than I'd previously eaten.
I don't review chocolate. I don't take notes or keep "scores" for personal use. If it's a new chocolate or one that I'm revisiting after some time away, I'll sit down with the bar (with an unfouled palate), start into it, and--rarely with any conscious effort at evaluation--react to it. Maybe that reaction is to spit the first bite into the trash can and drop the rest of the bar in after it. Maybe I finish a bite or two, then wrap up the rest to give to a coworker or one of my kids. If it's good, I'll finish the bar. If it's great, I'll finish the bar and make arrangements to buy more. That's the goal: finding bars that I want to return to again and again (and then doing so). I can articulate, after the fact, why I reacted to a chocolate the way I did; but the root of the evaluation is always instinctual (though with instinct conditioned by a basic understanding of cacao and craftsmanship and by years of palate habituation with large quantities of extraordinary chocolate).
As a consumer, I want it all--interesting, well-fermented cacao with no off flavors, skilled roasting, textbook texture. There are enough truly great bars out there that I don't feel the need to settle for "good cacao, shoddy craftsmanship" or vice versa.
Though I'm not dogmatic about it, I'm partial to the minimalist approach exemplified by DeVries, Domori, Rogue, Ritual, et al.--cacao mass and sugar only. Vanilla, added cocoa butter, and lecithin are acceptable in fine chocolate (though all can be abused), while CBEs and artificial sweeteners are not. Natural sweeteners other than refined sugar may be acceptable, in principle. (In practice, I've only seen one such bar--the 2011 Valrhona El Pedregal, using brown sugar--that was worth half a damn.) As for salt, if there's just enough to accentuate the flavor of the cacao, I wouldn't balk; if you can taste the salt, it's a flavored bar.
I think Art Pollard said it best: "Each and every step of the chocolate-making process is the most important step." Blow it at any individual stage and the quality potential is reduced, if not completely obliterated.
There are too many to name, but here are a few. For popular chocolate education, Maricel Presilla and her "New Taste of Chocolate." For community-building, Martin Christy (Seventy Percent), Clay Gordon (The Chocolate Life), and John Nanci (Chocolate Alchemy). For running my dream chocolate shop, Aubrey Lindley and Jesse Manis of Cacao (Portland, OR). For setting the pace for chocolate geekery in America, the members of the Manhattan Chocolate Society and the C-Spot. For championing Italian chocolate and gianduia, Gigi and Clara Padovani. For being the first and best of the new wave of American small batch bean-to-bar chocolate makers, Steve DeVries.
Making chocolate is like sewing your own clothes: it's labor intensive, but doesn't mean the end result will look, fit, or wear better than something off the rack at the local department store. The sad fact is that 9 out of 10 small bean-to-bar makers are charging two to three times Valrhona or Cluizel prices for chocolate that isn't even half as good. For startups that don't have the experience, know-how, or capital to both source great cacao and make well-crafted chocolate, I think there's something to be said for specialization and division of labor--for example, just focusing on sourcing and then partnering with an established maker to manufacture the chocolate. We've seen some of that in recent years (e.g., Felchlin manufacturing for Original Beans and Idilio, Pralus for Åkesson and Chuao Chocolatier, etc.), but there's no reason it couldn't be done on a smaller scale.