I faced the same dilemma as you, and ended up choosing Tier 1. I don't have dependents, though, so the cost was a little more reasonable. With a Tier 1 you can work outside jobs; there is a provision in Tier 2 policy that says you can do work that is related to your current job and limited in time (I forget the exact wording), but it still made me a bit nervous. In my line of work, it isn't unusual to do little jobs at other universities and I just didn't want to have to worry about it. Also, with Tier 1 you can choose when you will enter the country (assuming it is no more than three months after you date of application), whereas with Tier 2 you cannot enter until 14 days before your start date. I wanted to come over early to look for an apartment, etc. I was also very nervous about the discussion of limiting Tier 2 to shortage occupations (probably unnecessarily nervous, for what it's worth.) At any rate, those things may not apply to you.
Best of luck with your decision!
