YankeeJim:
I used the Srixon Z-Star yellows for years when I played a lot, buying used ones from a guy in Palm Springs that used to have a storefront near Palm Desert Resort. I also played very well with the Bridgestone B-330s when I was using white balls. Unfortunately he closed up shop a few years back.
Now that my swing speed is starting to slow, I'm not playing as much and I still have difficulty seeing the white balls in the air I'm not very particular as long as it's a bright color. My better rounds now seem to come with mid-range balls that have softer covers so I can control them around the greens.
Right now I have sleeves of new Wilson Smartcore, Bridgestone e5, Bridgestone e6, Maxfli Noodle and Srixon Soft Feel balls in the closet. A bag of about 2 dozen used Titleist Pro v1, too. My brother in law was here last month and brought a bunch of different balls he was trying before he settled on a yellow Callaway ball. He's in his 70s and his eyesight is going too.
They're all white but for free I don't particularly care if I lose them. I'm set for years.