I bike in the rain a lot. The most important gear I have for wet days isn't even rain gear. It's clear safety goggles for keeping the water out of my eyes and the right gloves so my hands don't freeze from wind chill. Both of these problems are probably worse than average for me because I tend to bike fast, so if you're more of a slow pedal kind of person they might be less important to you. Going fast in the rain is hard on the eyes and hands.
Pretty much any type of coat will work on light rain days. It will get wet but you should stay mostly dry.
I wear hiking rain paints if it's really pouring, but I usually don't bother. Maybe once a year? I figure my jeans will get damp, and then in an hour or so they'll be dry again, no big deal. I've never really understood the fascination with waterproofing everything, I figure if you go out in the rain you're supposed to get wet. Your ancestors have been getting wet in the rain for thousands of years and they all seemed to do just fine. Why are we suddenly made of sugar?