To start, it depends on what you want to do with it..
If you want to talk to your friends on the trail, or if you're road trippin' with another vehicle the walkie talkies are sufficient.
They do not require any modification to your vehicle.
Also, Walkie Talkies are also more portable, you can use them for many other things, like to keep track of friends and family on the mountain, snowboarding, skiing, or going to an amusement park, etc..
CB radios are good if you do a lot of driving on highways, etc.. You can find out about traffic delays, road closures, places to eat. The CB community is great.
Just a few ideas.
(Also, welcome to the board, this should be in the Electronics Section, not Tech.
One of the Moderaters will move it eventually)