I went back and forth on this before booking our trip on the Discovery in 2026. I agree with the PP that you probably cannot go wrong but here was our thought process. I have two young boys who will be 7 and 10 on the time of travel so that was a big factor. We ended up doing northbound.
Our first thought was to do the southbound for the idea of relaxing after the land excitement, but we were worried that it would be a little bit of a let down/boring for the kids. We thought that the cruise could just build excitement for the land portion. Also, if any excursions were cancelled or had poor conditions on the cruise portion we would have the ability to hopefully do one on land, like a whale watch or the sled dog experience.