At the very least, a religion that does not preach that it alone has exclusive truth; any religion that does not have a concept of hell; and any religion that does not have a god that acts like a human.
I'm cool with Unitarian Universalism, some forms of Taoism and Buddhism, and Quaker Christianity. Jainism is ok but I could never adapt to their diet, but at least they've gone 2500 years without any religious conflict.