I use generic except for Synthroid. More than one doctor suggested years ago that he/she would use the brand name for Synthroid. I don't know if it is still necessary, but I do pay $25 extra a month on my plan for using that drug--I pay more for the drug in my co-pay than i would for generic. Thyroid is essential to life, as i do not have a thyroid gland now,
so I have thought it worth it. I don't know though.
I do have requests in to my pharma to use certain drug mfr's for certain drugs if I need them. Like I use only Dr. Reddy brand Augmentin, an antibiotic, but the pharma keeps that one on hand anyway; I got sick from the other brand which tasted like onions. I use only two companies for two other drugs because those formulas , both generic, agree with me better than the other ones. Often there are many generics for one popular drug.