XIII-2 was at least coherent. It was just a post-Cocoon timeline that took you everywhere, not some weird brink of the world where only 4 locations exist. Having 2 new protagonists also kept it from falling in the trap that LR has. Serah and Noel didn't depend on the finished development of the original cast. Familiar faces hardly made appearances. It was all Serah/Noel/Caius/Yeuhl, who may have failed to write a compelling story, but at least made a pretty show of it.
The absolute worst part of XIII-2's storytelling was Lightning's little monologues, which were rare enough to roll your eyes over and move on with things. LR is practically built around them. They just cranked the melodrama on her character to max in XIII-2, and in LR they do it to everyone else in turn. We see Snow, Fang, Vanille, Hope, Sazh, etc... and they're all just ridiculously portrayed. It's nauseating stuff.
So I do prefer XIII-2's silly psuedoscience plot to this one. LR brings everything full circle and reunites the original cast, but it does some damn desperate legwork to get there.