Null Composure is an excellent Fusion Rifle (and even moreso in the Season after it shipped), and brought back the Reservoir Burst perk but PLUG ONE.1 and Glacioclasm can also get Reservoir Burst, and Cartesian Coordinate has better options for DPS.
The intent as of Season 12 is that a Pursuit weapon should be a solid weapon, roughly 70 percent of a “ god roll” in its archetype, with perk options that work well in PvP and PvE, and which can be reliably obtained without a huge grind. When we moved away from pinnacle weapons we didn't go into much detail, so we’d like to take a moment to clarify the move, and also introduce the Pursuit weapon for next season. They excited and motivated players, but they were expensive to build for Legendary weapons, and had some undesirable side-effects, such as PvP pinnacle weapons becoming mandatory in PvE (Recluse, Mountaintop), or becoming incredibly unpleasant to play against or so strong that no other weapons in the class could compete in PvP (Mountaintop, Not Forgotten). When pinnacle weapons were introduced, they were tuned and presented as being best-in-class weapons to act as rewards for players dedicated to a particular activity.