Congrats on having two great options.
I’d give thought to which environment you’d prefer to spend the next four years. Both are fine schools. BC is a Jesuit school with a large liberal arts core curriculum, located outside of Boston, and with a bigger sports scene as part of the ACC, . Lehigh is a secular school that is not by a major city, is more Greek Life oriented etc.
If you can visit/re-visit both school before making a decision that would be ideal. If not see if you can read up on the two schools in some good college guide books such as Fiske, Insiders Guide, Princeton Review – which you may be able to find in your guidance counselor’s office or in a library.