The old Japanese Waterline Consortiuum of 15-20 years ago has folded. The companies have begun competing head-to-head with an accompanying increase in quality.
You are right about the old Aoshima kits -- they were better than nothing, but often not much better. The PitRoad/Skywave product line does not have in their pedigree the Aoshima products -- they are their own work or are developed in concert with Trumpeter.
Some of the current PitRoad/Skywave kits do have in their pedigree some of the old Skywave kits. The USS Callaghan destroyer can be traced to the old Fletcher 2-fer Green Box kit.
Note too that Tamiya has taken over some of the old Skywave molds (O-Class destroyer, the Gato, and Zerstroyer).
Aoshima has done some rework on some of their kits. I understand that their Bismarck is much improved -- but the Dragon is still the preferred model (in plastic)
The Hasegawas really haven't been improved. Some have been reboxed with a whole hull & brass in a 'High Tech' fashion.
I also haven't seen much in the way of changes to the old Fujimi IJN line -- They have been doing modern USN -- bit they seem to be overpriced (IMO).
Tamiya has made some upgrades to their Yamato and have made several new releases -- but again no major rework on their destroyers, cruisers and service craft. They really didn't need too much.
If you look at the breadth and overall quality of the PitRoad product line I think you will be impressed. Yes, some kits are better than others, some are a bit dated, but overall quite good