I have a Fluke 8846A and it works well but as soon as you start working with the user interface of the Keysight 34465A you never want to go back to the 8846A.
The 8845A and 8846A are really dated instruments in comparison.
I am comparing it to my 34470A
The only advantage of the 8845A / 8846A that I can think of, is a much faster warmup time.
The 8846A shows stable measurements after only 60 seconds after power up
My 34470A needs at least 15 to 20 min after a cold start, to be stable in the ppm range.