To be honest I would prefer synths, only because I have seen quite a few orchestral concerts trying to play the music from oblivion and it didn't quite sound right..The best one was the Prague Symphony from Play! but even that didn't do a big enough justice to the music..here compare for yourself:
http://www.youtube.com/watch?v=nGyw_0IG5s0
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http://www.youtube.com/watch?v=1tuRz0wauQQ
Hi Borbarad, you've got a point here. I think it's not because of an orchestra being less capable of playing video game music (I really, REALLY liked the theme for Prince of Persia 2008 [[http://www.youtube.com/watch?v=mDcFFkFO900]] and the StarCraft II soundtrack), but because Soule doesn't compose for an orchestra, but for synthesizers (at least, that's how things sound to me).
For example, if you've ever played on a synthesizer workstation, there's programs in there that allow you to play an entire "orchestra". If you play really softly, there's only woodwinds and glockenspiel. A little bit harder and strings kick in. Then the brass. Then, if you really torture those keys, cymbals and timpani automatically kick in for a little bit of synth-y epicness =P .
Especially the faster songs from Soule sound like they're composed this way, and then pimped a little. They don't really make good use of the colouring and layering that a good orchestral arrangement does. If you listen to the PoP-song, there's subtle rhythmic strings accompanying the Eastern solo-instruments, countermelodies etc.. Or this version which is a little more up Oblivion's alley: http://www.youtube.com/watch?v=mAnUwON9oxU . Again, it feels much more palpable than the Oblivion main theme because it's been arranged with a real orchestra in mind.
Hopefully, you can make some sense out of this =) .