Imagine you're back in high school, planning to ask a fellow classmate out to the prom. You approach your potential date, "Would you be interested in going with me to the dance? You're one of my top choices."
Not very compelling...The same is true for letters of interest: I've had several applicants ask me if it's okay to say that an institution is "one of my top" picks.Avoid that type of language. Instead you can say something like "I would be thrilled to be at your institution," or " I’m confident I can make a positive contribution." In other words, you can stay honest while not shooting yourself in the foot.
I edit letters of interest and have been busy with them of late. Let me know if you need assistance.