You want several hand placement options that allow you to position your torso lower over the front end of your bike, or you prefer to ride most of the time with your hands placed on top of the bars, or you are most comfortable in between the tops and the drops, where your hands rest on top of the brake and shifter levers, called “riding the hoods”.
Comfort and stability are what you’re after. Flat bars will help keep your front end from dangerously swerving because of the greater control afforded by flat bars. Flat bars will also allow you to ride in a more upright position, which will not only ease strain on your back but will also make you slightly more visible when sharing the road with cars.
Handlebar designs range from more ergonomic to more aero and most everything in between. When choosing a handlebar for your bike, no matter if it’s flat or drop, you’ll need to take width into consideration as well. Go narrow if you want twitchier, more reactive steering. Go wider if you want more controlled steering.
Your handlebar is one of three points of contact between you and your bike (your saddle and pedals are the other two) and, in addition to giving you different hand positions when you ride, your handlebar choice: flat or drop bar, also has a tremendous impact on how your bike handles as well. So when choosing handlebars, put function before fashion because it’s far more fashionable to be able to stay upright on your bike!