Because you are going with a guardian angel doesn't mean you won't have much of an adventure. Consider the thought you might get targeted by demons (fallen angels) who are trying to hoax you into turning away from your guardian angel (and God). Let's say you did fall for their tempting ideas, your angel must now do whatever it takes to save you and return you to grace. It would be a difficult task for him/her to bring you back if you enjoy doing heinous acts alongside the demons. Let alone having to battle with the demons that keep you from him/her. On the other hand, you may ignore them resulting to them threatening you in spite. However, your angel is there to defend you. Yet again it may be a challenging quest to keep you safe from the harm they bring and the blasphemes they may tell you. So there is room for to have a detailed, epic and meaningful adventure with a guardian angel. :)
It is somewhat absurd to choose a fairy over a guardian angel. I mean, consider the greater extent of their power. Fairies, as depicted in most fictional tales, are usually limited to the rules of the mortal world where as a guardian angel would likely already reside in heaven. With an angel by our side you could possibly gain insight into the very realisation of oblivion itself; not to mention, that with the power of the heavens on your side you could potentially defy death in whatever situation you could imagine.
Fairies are from fairy tales......There are parents as guardians to show the right things to do, to give us advices. But all rights and nothing wrong in life makes it dull. So with a bit of fear and a lot of excitement I would like to go somewhere I've never gone, experience something which I've never experienced...Such golden opportunities seldom comes in life....
Fairies are magical so it would be better to take a fairy with you on an adventure. Although a guardian angel is probably more protective, a fairy would also give you companionship, while the angel would not be seen or heard. You would be able to learn from the fairy where as I don't think you will get much more than protection from an guardian angel.