Agfa Color *used* to be my favorite - until I experienced a *lot* of yellowing over time. I haven't used it recently, and to be fair, some of that could be from the RA4 chemicals. Back then I used a lot of Photocolor.... and be advised that I'm not sure that the chemicals had anything to do with it either.
For the last three or four years my color paper of choice has been Ilfocolor, and chemicals of choice are now JOBO/ Tetenal. JOBO went to Tetenal after Russell (which I liked *very much*) went out of business. Shelf life of the Tetenal Chemicals, using JOBOs "Protectan" has been excellent; they are easy to mix; and the results - all important - appear to be excellent.