I think it depends entirely on what type of life you are looking for. If you like stability in schedules, familiarity with routes and maybe being home more often then Spirit would win hands down. If you are looking for adventure, wandering the planet and having favorite places for food and beverage in just about any country you can name then Atlas is your choice. Either choice is fine if it's the right one for you. Like Beach nut said, if you are happy where you are then there's little reason to jump ship for the unknown. If you aren't then there are other options out there.