Reply To: what should I learn?

You cannot go wrong with Mesillas Yesharim, but I would also look for works by Rav Lopian, Rav Schmulevitz, and Rav Dessler. I go to a Sunday morning Hashkafa shiur that my Rov gives, and we cover works by the latter three. This year we are learning something by Rav Shmulevitz.