I was AV before I went pilot. I still use my taught skills 34 years later. Mechs are the same, just different skills.
I would say to you, take the tests at the recruiting offices and see which aptitude is best and what they offer you. Then smile if you get in, because you will enjoy both. Take every learning opportunity and get you licences done as early as possible. Not because you want to leave, but because it gives you more options in the future.
Then learn when and when not to party. Party at every opportunity.