I've never been crazy about how Call of Duty skips around with the main character.While it's kinda nifty to be able to use characters from different nations,I think it takes away from the storyline to keep switching up.That said I still like the story of both games,while at the same time I wish first person shooters had more plot/storyline development.
One thing I like better about Vegas is the two player co-op,This in my opinion is a feature that has been left out of too many great games.Developers need to realize not everyone has high speed internet where they live,therefore playing with a friend is their only option.
In my opinion I think Battlefield:Bad Company has alot to offer,descent weapon variety/with good iron sights,descent story,vehicle choice and control is good(who don't like to blow up shit with a tank),and some of the one liners are hilarious.The maps are pretty large too,so you have some options as to how to replay missions.