Hi! IMHO, it doesn't matter which side you sit on, because at times you will wish you were on the other side! I was on the left and the most memorable animal on that side was the rhino that actually started to charge the Safari ride, then pulled up short when he got close enough to see how big it was. We know it wasn't scripted, because the "Guide" CM was doing a lot of "umm-ing" and "well uhhh-ing" and we just sat tight and didn't move until Mr. R realized we were too big to tangle with. The next morning when we rode again, that part was no where in the script! I've never talked to anyone else who has been that had that same experience. We also saw giraffes on our side. The lions were on the right side, and I think the gorillas were, too, but it has been three years since we were there. Be sure to have a camera with a good zoom, if possible, because except for that rhino, I didn't get many close up shots.
Have a great trip!