If your purpose in reading sutras is to gain an intellectual understanding of the Dharma, you would be better advised to read sastras, or treatises, on the Dharma. Sastras were written by enlightened patriarchs, in a rigorous, systematic and logical manner. Buddhist concepts are presented in a more thorough and logical manner in sastras than in sutras.

Sutras, on the other hand, usually express just one or two ideas in different ways, no matter how long the sutra is. For example, the Mahaprajna Sutra consists of six hundred volumes, but the entire sutra speaks of only one concept: emptiness, or non-attachment. The same is true for most other sutras. Actually, the repetition of the same idea begins to get tiring. The repetition serves a specific purpose; it allows the Dharma concept to sink deeper and deeper into the reader's mind. The sutra presents the idea from numerous angles, and uses many illustrations and analogies. In essence, however, it is always the same concept. Because of the focus on a few ideas and the repetition, sutras are perfect for chanting. However, if you want to read a sutra for intellectual reasons, that's fine, too.

There are too many sutras to mention in this discussion. For Ch'an practitioners, I recommend the Heart Sutra. It is short and concise, but it is sufficient. I also recommend the Diamond Sutra. For reading purposes, the Heart Sutra is better, because it presents more concepts than the Diamond Sutra. On the other hand, it is better to chant the Diamond Sutra, precisely because it contains fewer concepts and more repetition.