The Meister, in my humble opinion, is one of the greatest Church mystic authors. He can be difficult to understand, and can be interpreted as saying some controversial things, like “God’s ground and my ground is the same ground,” whatever that means.
He is the most ‘eastern’ of western mystics, and his teaching that suffering stems from desire sounds a lot like Buddhism, which he had not connection with. He’s considered almost too mystical for his own good.
There’s a good collection of his works edited by Bernard McGinn. It’s something everyone interested in “religion” should engage with.
Some of the very good mystical Christian writings are accounts of saints activities and words. So I’d say writings about Catherine of Siena and Francis of Assisi should be quite fulfilling.
Good writings would be Teresa of Avila and John of the Cross.