I'm a bit hesitant to list my very brief list of other "trusted" developers, firstly because they aren't so much "trusted" as they are consistent with my own very personal and subjective standards, and secondly because no matter what company I list someone somewhere is going to take issue with them

With that in mind, I should preface this by saying that when I say I trust Stardock, I mean to say that I trust them across the board based on the points in my original post. When I say I "trust" these other developers, I mean that they have consistently produced games that meet with my
personal criteria for enjoyable, immersive games. They have let me down in other ways, however, particularly when it comes to stability and public relations. Stardock has never let me down in that regard to date.
With that out of the way, the only two other companies I would even think about using the word trust in the same sentence with (again, just for me personally, and not in all respects,) are Bioware and Bethsoft. I know the latter in particular will incite cries of "what are you smoking?" from some, but that's when you should scan above for the statement that: "They have let me down in other ways, however, particularly when it comes to stability and public relations. Stardock has never let me down in that regard to date."

I trust Bioware at least enough to continue producing RPGs with plots and NPCs that I personally find enjoyable and even moving, and I am just one of those people who really happens to take to their games' interfaces and play styles. They just work for me. They don't for everyone, and as I said, they have disappointed me in other ways. Nonetheless, I have never played a single Bioware game that I didn't enjoy immensely, and replay at least a half a dozen times.
Bethsoft is even more of a mixed bag. I was terrified after Morrowind's cross-platform success that their next TES title would be severely compromised for the sake of simplification and graphics. To a certain degree, it can be argued that this is precisely what happened. Nonetheless, the draw of TES for me personally is the enormity and freedom of exploration. There just aren't any other games that allow me to do what those games do, whether they let me do everything I wish they did or not. For that reason, I at least trust Bethsoft to produce large worlds in which the player is allowed to explore freely and in an open-ended fashion. They have let me down in other ways, of course, both in the game, and outside it. In particular, I am somewhat critical of their public relations and of course, their legendary stability issues, however I have to temper that by thinking about the size and complexity of the game.
So, in conclusion, those are the only other two companies who I can even compare to Stardock in terms of the word "trust," but we're still talking about completely different leagues in my personal opinion and based on personal experience. I will buy any RPG Bioware makes, short of purely action RPG. I will buy any TES games Bethsoft makes, though I may wait a few months for initial patches and tweaks (a suggestion I make for anyone considering future TES titles.) That's as far as that "trust" goes, however.
Stardock has impressed upon me something more than just an expectation of good games. They strike me as individuals I can place my faith in across the board, from customer service, to player feedback response, to software support, to sheer spirit. That may sound lame, but I really get the feeling that Stardock actually wants to treat its customers with respect. That's a different, and more profound sort of trust that good games alone just can't buy in my opinion.