As you know, a bathroom with a shower & tub is considered a high-humidity room. A latex product such as Stain Kilz for primer is good. BUT, since you've already primed, hopefully you've used a primer that will 'block' moisture from getting to the green / blue board underneath. (I'm assuming you're NOT painting a 1/2 bath in which you'd have standard Drywall.)
After that, the top coat should be a mold & mildew-resistant paint. I suggest you buy the paint that already has this preventative in it. Latex based paint is fine. If you were painting the wall over or around the stove in the kitchen, I'd recommend something different. The latex-based paints made today are easy to clean and don't need much scrubbing when in need. As for a MFGR, I'm partial to Finnaren & Haley. It, like MAB, Sherwin-William, and the like, can be found in the Yellow Pages under Paint-Retail. For real good, quality paint, you're gonna have to buy your paint from these retailers. Even though my 3.5 year old daughter is a stock holder of Home Depot (HD), I don't buy my paint from them. These 'competitive products' are speced-out by the Home Center / Sears / Wallmart stores, and don't compete in quality to the Retail Stores out in the street. Just tell the retailer what you're painting and they'll tell you what roller and brush and paint should be used.
There you have my $.02. My best to ya and hope this helps.
PS: Yes, I took my kid's Christmas, Birthday, Christening $$$, etc., etc., and bought some HD stock 2 years ago. So far, so good. Her McDonald's stock isn't faring as well but hopefully in 10+ more years, it will have done fine!