I think it's simply a matter of what you like - how you like a horse to move and what you plan to do with your riding.
Western is a slower gait - the walk is slow, the jog is slower and the lope is easy. And the horses are picked with that in mind. If you were to go to a show and watch both events, even the beginner/open ones, you'd see a vast difference between the two, besides the tack. Western can be geared towards pleasure, IMO. When you trail ride, chances are you'll be riding it on a western saddle.
Western saddles are heavier. In fact, they're gynormous! They'll put muscle on you lugging them back and forth from the tack room. Unless you have a petite horse, you're going to be amazed at how heavy they are.
I personally like Western riding, I like the challenges, I like the freedom of using neck reining or direct reining. I like that I can use English type aids AND Western aids. You can't do that with English. he he
I enjoy pattern work and side passing and doing things like that. I also like the saddle - it's big and deep - like riding in a big fat recliner.
I think Western is more personal - more you and the horse kind of thing - but that could be me. I'm always about the horse I ride, always trying to create a working relationship.
I confess I love an English saddle because there is a lot of contact with the horse. Aussie saddles are said to be the best of both worlds but I've never ridden one so I can't comment.
Take a couple of lessons. Many riders have done both and find it beneficial. All roads lead to Rome - a good lesson is a good lesson - working on your aids, balance and various skills, communicating with your horse. That's what it's about.