Go for the ramp, I say. My mare is hard to load with a ramp. Take the ramp away and she refuses to go near the back of it. I think it's scarier. Even if your horses will load into a ramp-less, I'd go for ramp, who says you're not going to get a silly horse someday?! Haha.
It is not enough for a man to know how to ride; he must know how to fall.