Asking what kind of bike you should buy is like asking what kind of car you should buy. Depending on how you plan to use it is the major factor. If you're just looking for something to casually ride around town, I'd suggest an upright straight bar bike like a hybrid. If you're looking to ride long distances (say, 40 miles or more) on pavement, I'd suggest a dedicated road bike. If you plan to ride gravel or trails, I'd suggest a gravel or mountain bike.