Which offer to take?

I got two offers and had hard time to decide which one to take. Could you please provide some suggestions?

#1, mid size military software comany (requires security clearance). I came from mainland China and had some concern in choosing this type of job. Anyone has experience working in this type of company?

#2, mid size telecommunication VoIP company, new team, lead role. I don't have experienc in this area. Is it useful for finding a similar job in the future?

I might get another offer in a big company in Web Technology. The salaries will be roughly the same for all of them.

I am in my early 40s so stability is important. And also the better job market protential is very important in my decision. Which one will you choose?

I have to make the decision this week.
Thanks in advance!