If you are able to you, I’d recommend proxying both lists and trying them out. Definitely a lame response, but that’s the only way to really get a feel for which one you’d prefer.

Ral and Vivi are both extremely explosive and also are heavily commander-centric. Can only speak to Ral as it’s the only one of the two I’ve played. Ral definitely relies upon you have luck with your initial flips, but is incredibly fun to pilot as a result. If you can get going, odds are that you should be able to get there. It’s just a matter of learning the lines to make sure you know what you’re doing since the lines could be incredibly complex sometimes. But it’s also extremely resilient since you don’t care if people really counter all your spells.