Hi,
Having worked for both as crew I would say BA all the way. If you are only going to fly for a couple of years then go for VS as you will see the world quickly but at the price of any money.
If you are going to fly as a career long term than go BA. Better money to start and the wait for long haul LHR is only around 2 years at the mo. Then you will realy see the whole world. And BA Shorthaul is great fun with plenty of nightstops too.
BA BA BA