How do I choose a company to use for my retirement plan?

I plan to open a 403(b) in August. I have been told that mutual funds are better (and cheaper) than annuities, and so that is what I want to put my money. (I don't intend this question to be a mutual fund vs. annuity debate). My school district sponsors 20 retirement planning companies, and their websites don't seem to distinguish the competition. Some companies include Fidelity, Primerica, Vanguard, Metro Life, Equitable, Putnam, etc. How do I choose which company is best for me whether or not I end up getting mutual funds or annuities?
I teach in Florida. We have the Florida Retirement System (FRS). My school district puts money into that, which I can choose either to be a pension (with benefits after 6 years of service) or an investment plan (with benefits after 1 year). I choose the investment plan because I don't know if I will be in teaching in the long-run or if I will at least be in Florida for 6 years to get the pension benefit. According to everyone, the FRS will not be enough, so we have the option of opening up a 403(b) plan with one of these companies to supplement the FRS money. There is no matching in this 403(b).
I am 23 years old.