Since you will be hunting open areas as well as wooded, a rifle might suit you best. There are many calibers that work well for whitetails. Some of the more popular ones are .30-06, .308, .270, 7mm. Any of these would be a good choice. Personally I like the .30-06, since that' s what I hunt with. There is a very wide range of bullet choices available for that caliber. If you have any friends that own rifles, see if you can shoot a couple different calibers to get an idea of what you personally like.