This discussion may contain spoilers!
When I say "greatest" I'm not just referencing the fact that they make Sam & Max games, but mostly referencing the way they treat their fanbase, mostly though their forums. See, with most companies' forums, there is very little interaction from employees at said company, pretty much the only interaction comes in the form of official announcements and some suit posting " does not comment on rumors or speculation.".
Now Telltale is a vastly different beast altogether, albeit a much more social beast. Not only do you have employees of the company posting on the forums, but they're posting frequently. And not only that! They're freely offering up little tidbits (i.e who worked on what for a particular episode, plans for future episodes, what they changed their minds on) and actually giving satisfying answers to their fan's questions! I was actually quite shocked when I started reading these forums and noticed all this. I also appreciate the casual tone that Telltale word their announcements in, as though it was written by a normal person, not some head of marketing suit. It gives me a "connection" to the studio, while at the same time not sounding "forced", the results of cold-hearted "market research" (looking at you Microsoft at Sony).
You can really feel the passion for both their work, as well as the love for their fanbase (which, as I think we all know, is what's selling Sam & Max!) that Telltale exhibits. One event in particular that stands out to me is where someone, out of curiosity, asked for a top-down view of Sam & Max's DeSoto. Almost instantly, Jake posts a render of just what was asked for. This was obviously no small task, programs would need to be opened, renders rendered, tasks which most studios would consider a waste of company time. All for a single fan. You'd never get that kinda thing from any other studio, it lends Telltale a down-to-Earth, indy-like tone which the video game industry needs more of.
And finally, they really seem to listen to fans. I know most companies say they listen to customer comments, but you know they very rarely do. Where as with Telltale, they've taken a general consensus from the forum populace, (that the Soda Poppers are very annoying) and turned it not only into a joke (the Soda Poppers are more evil then Satan himself!) but the ending to the final episode! And not only that, they let us know that they are listening, and what they think of fan's suggestions.
So congratulations Telltale! Give yourselves a round of applause! You've got yourself a fine studio, with top-notch customer relations, a shining beacon of how a company should interact with their fanbase! Keep up the great work, and don't go changing on us!