It is very difficult for me to compare Obsidian to Larian simply because of the number of different type of games execute by Obsidian. I kind of wished you had mention some games because I'm not sure if we are talking about nwn-2; jade empire; prototype; Dungeon Siege iii; ...
-
Also Larian games are some what different (dks, divinity, beyond divinity); but I tend to find from the list of games I mentioned (there might be others); that Larian games are a bit more open world (more freedom of path) but the stories a bit more constrained (obsidian seems to provide more choices/consequence of choice); though I believe that Larian has stated several times that in D:OS they intend to focus or at least add greater consequence of choice for side quests (not sure if this will impact main quest).
-
The other thing that is a bit unfair in the comparison is that Obsidian history is much richer (more games; and trials at different approaches to story telling); esp if you consider the pre-obsidian games that the major players (Chris Avellone, ...) have explored. That is to say it seems to me that Larian has relatively few games and they are still refining their style (I expect D:OS to be an evolution on DKS story telling which was an evolution from divinity/beyond divinity). It is unfortunate that they had a bit of money issue causing the evolution to be a bit slower. Conversely I am sure that Obsidian story telling has been some what constrained by publisher pressure (so it will be interesting to see what becomes of Project eternity).
-
I did not mention fallout las vegas in my list above since I have not played the game but of the games I mentioned i really liked DKS best though as I think back on it I think it perhaps lacked a bit of choice/consequence mechanics that some prefer. In fact I can't really think of any RPG that have very strong choice/consequence machanics (in a grand scscheme; but to hear xile talk about Wastland 2 that might be such a game - they claim that choices you make will result in many hours (20+) of branches in the story line - though it remains to see how it executes.
-
I will say that I have very high hope for wasteland 2; D:OS and project eternity (perhaps too high as I cannot see how they can all be successful from a perspective of statistics) and perhaps this new age of self funding/public funding (or simply non-publisher funding) will also bring in a new age of RPG gaming.

(of course as a player who often tries to completely finish a game we will now have to accept that is just not possible because not all 'quests' can be performed per session due to branching smile )