Major Vs. Cargo? What's the real deal?

I've been trying to figure out whether I want to aim my career at Cargo, or a Major airline. The two Cargo Airlines I've looked at are USP, and FedEx. The Majors I've looked at are Air Transat, Air Canada, and WestJet. Can any of you give me some insight into which path would be better...wheather it be due to pay, benefits, hours and so on? What's the deal?

Always,

Dreamer