Be very careful. Even some that are BFA acredited are difficult to work. The power always lies with the Franchisor who can be more strict and picky than an employer.
It's often the case that you could actually set up your own business in the same line of work without the massive upfront costs of a franchise fee (for joining) and without the monthly management service fee that they will probably take as a percentage of your turniver (not profit). 80% of the time you actually get very little for your money.
You won't earn the money that they claim, or if you do it will take much longer to get there.
Of course, there are some great ones like McDonalds and Burger King, but then you're looking at serious investment.
Out of interest, which ones are you looking at?