My vote goes for Bioware right now, and oddly enough they're the developper whose games I've gotten into last.
Bethedsa does create some very interesting concepts, and their open-world RPG design is very fun in its own way... alas, I'm more interested in good storytellings. Oblivion has provided a ton of entertainment over the past few years, but it has largely been done as a diversion and/or to satisfy my desire to do some random exploring; and maybe the fun of trying out the many various mods. I'll definitely be getting (and enjoying) Skyrim, but it's looking like I'll be treating it as something similar to Oblivion - a fun diversion, but one which lacks a strong storyline to drive it. I haven't really bothered with the Fallout games (not interested in the setting), and I've played barely any of Morrowind as well (tried Oblivion first, and while Morrowind supposedly does thing better... it's rather inaccessible in comparison and doesn't manage to hold my interest long enough).
As I had noted, I enjoy good stories in my games; so Square Enix should be the obvious choice, right? JRPGs may be overly linear, but still have some of the best stories in gaming... unfortuantely, Square Enix hasn't been doing well the past several years. To be perfectly honest, the slip began roughly around when Squaresoft and Enix merged to become the current company; there were a few good games in the first few years after that, but afterwards it's been rather underwhelming. Looking back at the classics Squaresoft created, those are some of my favourite games of all time. Heck, I've only recently gotten around to trying Xenogears (I picked up a PS1 copy of the game years ago, it's been sitting around simply because I've been playing more modern games instead) and I'm greatly enjoying it. However, looking at their more recent installments hasn't been so good; just about all the Final Fantasy titles after FFX hasn't managed to hold my interest for very long. Square Enix appears to be trying to re-invent the series (repeatedly) to better fit into the modern era, but it just isn't working; the storylines are also lacking the charm of the older titles. There's so much potential in Square, but they just can't seem to get it right (for me, at least).
And finally, we have Bioware. Perhaps it's my misfortune to have missed out on all of their older and supposedly "better" games, but I'm finding that their recent titles have been outstanding (though I won't deny that DA2 was a disappointment). The Mass Effect series is a damned-near perfect blend of great (action-oriented) gameplay and outstanding storytelling; and it presents a great deal of choice about the storyline as well, not just concerning character progression. Dragon Age: Origins is another title I found to be outstanding, with yet another great storyline that you can affect a great deal. Even if Bioware's games all seem to follow a tried-and-true formula, it's done well enough that the only people who give a damn are those who are trying to come off as smart by being a critic that completely ignores the merits of a product for silly reasons.
