I will mention (again) the Kalavinka Press series. http://www.kalavinka.com/
Excepting the two meditation books & the Stories volume, everything there is seminal and clear and focused on the bodhisattva path.
The "Friendly Letter" of Nagarjuna was a favored primer for aspiring bodhisattvas in India long ago - so why not study it first? Kalavinka's edition has three translations - all older than any Tibetan version.
I am fond of Vasubandhu's work on bodhichitta and N.'s Bodhisambhara Shastra
which latter Dharmamitra has in two versions: abridged & a full commentary by Bhikshu Vasitva.
Since Nagarjuna is often thought of as the "founder" of Mahayana his shorter texts should be at the top of any list.
Basically, there is not even one Buddha; there is only great wisdom. Bodhisattva Hsuan Hua