What version(s) of Adobe Photoshop is/are compatible with El Capitan?

At least Photoshop CC 2015 is compatible with OS X El Capitan. There are some issues with this version, but Adobe has provided a fix for all of them -> https://helpx.adobe.com/photoshop/kb/photoshop-and-el-capitan-mac-os-10-11.html

Respecting to CS versions, some users are experiencing serious issues, while others are running it with no issues. In this case, I'd recommend you to install OS X El Capitan on a separate partition before upgrading your main OS X system, or stay with the version you are running now.

FWIW, I am currently using PS CS6 on OS X 10.11.2 with a

late 2013 27" iMac with 3.2GHz i5 and NVIDIA GeForce GT 755M 1024 MB.

The only issue that I have is that Bridge does not recognize any cameras

when plugged in.

For me anyway, my workaround is Canon's software to download stuff off my

Powershot SX40 and Nikon View NX-i to download images from my D3200.

Photoshop CS3 is compatible. However, one must install Apple's legacy Java 6 runtime for it to work: Download Java for OS X 2015-001