Back when I had no mind games, wouldn't DI, and would not use aerials very often, I used Falco because he had the Dthrow shine(which shouldn't work normally, but my opponents did not DI) and because his Fsmash was powerful and fast. Marth was my second best character because I liked his Fsmash a lot and when I used dash attack to Fsmash, I thought "wow what an awesome combo."
Just about 5 months ago, I learned about advanced techniques and began to watch some combo vids. What started me on the path of maining as Marth was the vid Wound of the Wind and seeing his high position in the tier list. I had also seen Soldier of Fortune, but I found Marth more enjoyable to play as. I did not know any of the pro Marth players at first, so I did not know that the world champion played as Marth.
Fortunately, I learned that winning against good opponents is more than just comboing, but I still liked Marth over Fox and Falco b4 I realized this simply because I received more satisfaction by playing as Marth.