Who are the main western philosophers who acknowledge the importance of meditation, self-discovery(know yourself) and the realization of your own mind-habits and emotional responses?
You might usefully try :
John R. Sommerfeldt, 'Meditation as the Path to Humility in the Thought of Bernard of Clairvaux', Mystics Quarterly, Vol. 15, No. 4 (December 1989), pp. 177-183.
Richard Douglas Jordan, 'Thomas Traherne and the Art of Meditation', Journal of the History of Ideas, Vol. 46, No. 3 (Jul. - Sep., 1985), pp. 381-403.
John Malcolm Wallace, 'Thomas Traherne and the Structure of Meditation', ELH, Vol. 25, No. 2 (Jun., 1958), pp. 79-89.
Finley, J.: 2000, The Contemplative Heart (Sorin Books, Notre Dame, IN).
Kabat-Zinn, Jon. 2005. Coming to Our Senses: Healing Ourselves and the World Through Mindfulness . New York: Hyperion.
Michal Pagis, Embodied Self-Reflexivity, Social Psychology Quarterly Vol. 72, No. 3 (Sep., 2009), pp. 265-283.
Brian Stock, 'Commentary: Reading and Healing: Reading, Healing, and the History of Western Meditation', New Literary History, Vol. 37, No. 3, Reading and Healing (Summer, 2006), pp. 643-654.
John D. Lyons, 'Meditation and the Inner Voice', New Literary History, Vol. 37, No. 3, Reading and Healing (Summer, 2006), pp. 525-538.
The Delphic maxim is truly ancient, but it's meaning and implications are very much open to dispute.
Stoics practiced meditations on various topics, and indeed that is why Marcus Aurelius' memoir was titled 'Meditations' (although, I guess Descartes used the same title, without the same practices..). Stoic practices are very much focused on active self-observation and reforming.
There is a tradition of meditational prayer in Christianity, especially in the practices of the anchorite https://en.m.wikipedia.org/wiki/Desert_Fathers and more broadly in the https://en.m.wikipedia.org/wiki/Hesychasm of the Eastern Church.
There is a lot of subtlety in differences between how different traditions approach meditation, and precise practices. The stoic practices are like vipassana meditation, and the Desert Fathers are a rare example of Western practices like samatha meditation. But I would say otherwise, meditation and guided self-reflection on the workings of the mind has been rare in the West, until modern times directly influenced by Eastern thought.