Having owned both CS-88A's and Dynaco A-25's and hearing several specimen of CS-99, I would say it would really depend on your tastes.
The A-25 is going to be a little mellower and smoother, but not as large.
There will also be a difference in tone, with the CS-99's being a little dryer sounding (more “studio monitor” like), and the A-25's more on the sweet side (more “classic hi-fi” like).
Bass will be about the same at lower to medium listening levels, but the larger woofer in the Pioneers will be a definite advantage at higher levels (though one would think the reverse would be true). The A-25 will probably handle more power before audible distortion sets in due to the proportionately longer excursion of the cone.
For a mellow, house filling sound, you will likely prefer the A-25’s. For louder rock our country, the CS-99’s will have the edge.