Of the three, I like the CHR style best. I find Velocity too dark with too much contrast, Default has too little. It is easier to see which folders have new posts with the white "bubble".....the Default icons are much harder to read. It has taken a while to get used to the new format and, while I would prefer the old site, I realize that it is gone and I might as well get used to the newer version. Like Bat, I'm 70 and would have preferred not to change, but I like this site too much not to adapt.
One interesting thing is that when I accessed the site from IE i always got the default version whereas with Firefox I got the CHR version. Now I know why. It's great to have a choice.