There is an argument to be made that the 777 st Southern is a worse choice for a young new hire than the 737. You will never upgrade, so always lack PIC time to move on to a better job. But you will also make much more money than you would starting over at a regional, leaving you trapped in your position. Unable to upgrade, unable to move on. You'll make enough to get by, but if you should ever meet someone and get married, which frankly is going to be damn near impossible being gone so much, you won't be making enough to fully support a family. Your spouse will be a de facto single parent most of the time, and that will always be a source of friction in your life.
So, in addition to accelerated aging due to the inhuman schedule, dying of cancer early due to increased radiation exposure from spending 1000+ hours a year in the upper atmosphere, you can also suffer alone due to lack any lasting human relationships beyond what you can rent in Wan Chai.
Hindsight being 20/20, I would never have left my first regional.
If you're at any Regional, don't come to Southern. Three years to upgrade is better than twenty. Your crappy regional contract is 1000% better than our crappy supplemental contract. Your managerial leaches are more competent than our managerial leaches.