I would not, at this point, sweat the union thing. Before you can make a choice, you have to be qualified first.
Right now, it's all about the training. Training through the union is superb. It is universally recognised. It can result in a college degree.
Nor would I, at this point, worry to much about "a few years down the road." Fact is, you will find learning the trade a great preparation for several other things. For example, your understanding of jobsites can set the stage for becomming an inspector or project manager when you're a bit older, and running up and down ladders all day has lost its' charm.
Think of a "journeyman card" as the beginning of the journey, rather than the end!
