There isn't ONE answer to your question for everybody. The right answer depends on your own geographic or social constraints, your aspirations, your risk tolerance, your prior experience.... A whole multitude of variables.

For example, the regional where you can progress most quickly might have cr@ppy pay and work rules and overall quality of life, but it may get you too the majors years before a regional that you would find preferable if another economic downturn trapped you at a regional for a decade.

'Flow' generally is a sucker play, like the house edge on slot machines, the extended warranty, or that true coat they put on at the factory, but if you've got three DUIs, four training failures, a FAR violation or two, and a breaking and entering conviction, cr@ppy though it is, it may be your ONLY possibility of getting to the majors.

Everyone's situation is different.