Topic worth leveling?
If you're choosing a class strictly based on your chances of getting into a PUG raid, pick a hybrid. Hybrids are able to fill more than one role, which will increase the odds that a given raid group needs something you can give them.
It's important to know what you're doing - getting a reputation for being good at what you do will get you invited. But DPS is the first role to be fully covered in most raid groups. If they're full on DPS it doesn't matter how good you are at it; they're going to pass you over for someone who can do what they need done.