Oblivion has the bigger cities... Skyrim has... well that's already been covered in this topic.
Oblivion GOTY will ultimately have a bit more to do and some more going for it, because Shivering Isles, but...
ignore all that. If you want a game to get into Elder Scrolls with, go with Skyrim. Both games have wonderful and awesome worlds to explore. However, Oblivion has this terrible level up system that you basically have to fight with and figure out how to trick before you can just enjoy the damn game world. In a lot of games that level up system would have just flat out ruined the thing entirely, but the stuff behind that in Oblivion was awesome enough to make it worth it. But in Skyrim the level up stuff just works, and you should be able to just go ahead and enjoy the world on your first character. Play Skyrim first. If you enjoy it, then later go back to Oblivion and just do some research on dealing with it's leveling beforehand.
On the other other hand, Oblivion is a lot cheaper, and if you have the patience to learn an annoying leveling system before you can really enjoy the game behind it then I guess why not?
Oblivion GOTY will ultimately have a bit more to do and some more going for it, because Shivering Isles, but...
ignore all that. If you want a game to get into Elder Scrolls with, go with Skyrim. Both games have wonderful and awesome worlds to explore. However, Oblivion has this terrible level up system that you basically have to fight with and figure out how to trick before you can just enjoy the damn game world. In a lot of games that level up system would have just flat out ruined the thing entirely, but the stuff behind that in Oblivion was awesome enough to make it worth it. But in Skyrim the level up stuff just works, and you should be able to just go ahead and enjoy the world on your first character. Play Skyrim first. If you enjoy it, then later go back to Oblivion and just do some research on dealing with it's leveling beforehand.
On the other other hand, Oblivion is a lot cheaper, and if you have the patience to learn an annoying leveling system before you can really enjoy the game behind it then I guess why not?