Our very first cruise was 5-nt Western on Magic. We decided to try Fantasy next and choose Eastern with SWDAS. DH and I much preferred Magic. The 5 night didn't really feel that much shorter, maybe having 2 sea days helped. For our next cruise, we really wanted Magic again or try Wonder. The Magic sailings didn't match up with the dates we needed. We almost settled on 5 nt Baja on Wonder but after researching the ports, we opted against. We are doing Fantasy Eastern again but this time hope to get to Tortola.
So, to answer your question- I'd pick Magic.
So, to answer your question- I'd pick Magic.