Of those, I've only been on Symphony. It's my very favorite Royal ship. There is so much to do from amenities (dry slide, waterslides, zipline, laser tag, pools, flowrider, mini golf, etc) to areas to explore, tons of restaurants that are both included and specialty, shows are amazing, and just the decor and all is beautiful.
I've been on sister ships of Explorer (Navigator, Voyager and Mariner) and if you don't like large ships, then you may prefer the size. It didn't make it's amplification, but I assume it has the basic Royal features. No Broadway show.
Liberty would be in-between for size. I've been on Indy, a sister ship.
It depends what you want. Do you prefer a larger ship with tons to do? Do you want slides and things? Or do you prefer something more intimate and just want to rest by the pool and participate in some of the activities?
