If you like the management team in company A, and you are confident in their business plan and product line. I guess you can probably join a winner without sacrificing anything.
Otherwise, company B would not only be a safe bet, but also a better choice. Remember, nobody says you have to be there forever. There will be more opportunities when you have more experience. Besides, why do you think there is no chance to move up? Isn't that one of the strong argument of potential HaiGuis?