TCS vs Accenture which offer to choose, pls help

Which offer to choose, TCS vs Accenture? How is the market / business side of things in these two? Stability, work culture, project work, tech stack, fluidity in switching projects are important for me along with other given parameters like better salary, chances of getting promotions, good hike work hard and smart, flexible in terms of location/ mix of WFH-WFO hybrid Would saying NO to either of these burn my chances for future hire? If yes, how to avoid that. Should call hr/write a mail/both. How many days before must I mention upfront 'will not join'?