Depends on your appetite for risk. B will likely pay you in stock and/or stock options of which some portion will immediately vest and be sellable (albeit with

Depends on your appetite for risk. B will likely pay you in stock and/or stock options of which some portion will immediately vest and be sellable (albeit with substantial taxation). But at least it will be liquid. A and C will both likely pay you in stock options or units. But since the companies are not public, you won't realize this wealth until a liquidity event (like an IPO or a buyout). That maybe years away, and a lot can happen between now and then. All three options can be made less risky if they offer cash, but of the three, A and B are likely to offer more cash. Career wise, it's going to be very dependent on who the acquirer is and has less to do with the stage they are in and more to do with their culture around acquisitions. They might want your technology or they might want you, but it's very rare that they'll want both.