Find a startup with financial backing and a significant runway (like 2 years). They have usually put out enough fires already to have some stability. With enough runway, the focus will shift from day-to-day to long term code stability and design decisions. It will still move quickly, but the likelihood of put-everything-on-hold-and-pull-an-all-nighter decreases. Avoiding burnout is a priority, as the founders came pretty close just to get the money. You won't see a simple 9-5, but you will see keeping weekends free and keeping a balance between home and work.