Current Yamaha CDC-C300 vs Onkyo changer
If you want a new CD changer, I believe the C600 (new) is the best available. I have had one for about a year and it has performed flawlessly. I also have 2 of the older precursor Onkyo DX-380 (Goodwill - cheap). No problems with them yet but they are used less on other systems. One is used parallel to a new Onkyo C-7030 single and I haven't noticed a SQ difference yet between the two. If you don't have the prejudice against changers, I think the Yamaha is the best option as the current Onkyo 390 has supposedly had more quality problems than the Yamaha.
Goodwills however have CD changers all the time, including many Yamahas, Onkyo's, older Sonys, (even Technics or Toshiba DVD changers), so if you have patience, you could pick up a couple with some as back ups for their eventual laser breakdown.