What Notation for Teaching Boolean Logic?
If your students were a bit older, I'd be more comfortable with the following, but suggest it anyway.

There is an advantage for a student to know that the concepts exist independent of any notation and that historically  notations have differed based on use and context. 

I would, myself, provide them with a handout giving names to the concepts and various notations used for each. Then, I'd use the various symbols as naturally as possible, responding to the inevitable questions. 

The only caveat would be that you don't mix the different systems in any given lecture/conversation. You should also suggest that the students be consistent as well. 

The rationale here is that students will likely see different symbols sooner rather than later if they do any reading or research outside your instruction. It is better that they have some preparation and at least a hint that the terminology isn't entirely consistent or standardized. 

Some of the terminology, by the way, such as + for "or" is actually tied to the concepts in interesting ways. For example, the similar shape of ∧ and ∩ help students understand the relationship between logic and set theory. Some of the symbols, on the other hand, were chosen for no better reason than that they exist on common input devices such as keyboards.