Oat milk for me, too. I've found there's quite a bit of variation between brands, though. I like the thicker, creamier varieties that have just a touch of sweetness.

The rice milk I've tried has been largely flavorless; soy milk has that "soy milk" flavor that I don't hate, but I'm not really into; and the nut milks I've tried (especially almond milk) have an odd, slight sourness that I find really unpleasant. I'd like coconut milk more if it tasted more coconutty.