Currently in my bag, I have:
4 Yellow/Gold
3 Red
2 Orange
2 Pink
1 very pale (almost white) pink
1 White
I generally agree that pink is the best color, and probably orange is the second best, but a good popping yellow isn't far behind, and when I started, my husband was getting Orange discs, and my other friends were getting pink discs. Through luck and some conscious decision, Yellow became my sort of default color, and is why I have more yellow than any other color.
2 of my yellow discs are Innova DX/R-Pro yellow. Like Crayola Yellow. They don't SUPER pop, but show up pretty well. One is a transparent Champion yellow that SCREAMS in sunlight. One is a GStar swirling metallic gold. Pretty, but not a super popping color.
One of my red discs is transparent Champion, and pops pretty well in bright light, but hides pretty well in shadow. My other two reds are Star plastic, and like Crayola 'Red'. They are surprisingly hard to see, for being red.
One of my pinks is neon pink transparent Lucid plastic, and is SCREAMING pink. It's so bright I can hear it. It's awesome, and seems to get brighter near sunset. Amazing. The other is Star Plastic, and just a pale pink, but seems to be pretty visible.
I have one Champion Orange that is very bright, and one Lucid orange disc that is not all that intense.
I played Wilmore Park in St. Louis today, in gusting wind, and they haven't mowed recently, leaving the grass like a foot high, and shots occasionally going way off course. I sometimes found myself selecting my disc based on color, more than flight properties, just so i had a good chance of finding it. In fact, on one shot where I selected for flight instead of color, I spent about 5 minutes pacing around the landing zone, looking for my disc.
And the other day, we played the same course, and my hubby was standing near his lie, looked down, and picked up a black Blizzard Katana. No name, number. So... (shrug). How to lose a disc. Step one: buy a BLACK driver. Step 2: Throw it. Ever.
I've said it before elsewhere. The worst disc I ever saw was a champion disc, fairly transparent, in coffee brown. But black is pretty terrible too. Not like solid glossy black, just very slightly transparent black. So it'll blend in better. A friend of mine got a tie-dye disc and learned a neat lesson on 'Optical Color Mixing', such that those brilliant blue, red, and yellow swirls all mix into a neutral brown at a range of 20 feet.
Since I'm fairly new, and still trying a lot of stuff out, I keep getting stuff used from Play It Again Sports. You don't always get a great choice of color from their used bins, but I have passed up otherwise great discs for cheap just because they were a ridiculously easy-to-lose color.