Welcome. This is a place with a lot of helpful folks.
What you love will be up to you, gained through trying different things. Be sure to try a wide range of subjects. Cars, airplanes, armor, sci-fi, Gundam, whatever. Liking what you end up with is important.
As for challenge, it's overcoming obstacles. A lot of modelers, myself included, find beating an old AMT muscle car kit into shape, or a Hawk airplane kit from the 50's, is the true test of skill.