Normally I'd say Rose Jaipur since you already have rouge casaque. But if RJ is truly neon-ish, you may find it hard to wear, especially on a large Kelly. The vermillion is different enough from rouge casaque (and on a different style of bag), yet possibly more in your comfort zone than a neon coral.
I'm with ouija board. If you like RC and find it's easy to match like me then vermillion will be easy to wear. But if you want a color that's different than what you already own then go with RJ. G'luck deciding.