I've used ClipMate for almost 20 years. I love it. When the developer went AWOL, I tried ClipCache. I was impressed with how much better it was at handling graphics and unicode, but there were two features I missed so much that I went back to using ClipMate, and I have continued to use it happily. The two features I use a lot and can't seem to live without are PowerPaste and the ClipBar. PowerPaste lets me rapidly paste consecutive clips into a document, a form, a website, etc. ClipCache has a similar feature, but I found it less reliable than ClipMate's. As for the ClipBar, it sits on the bottom bar or task bar and shows me the most recent clip without my having to move or click on the mouse. I simply glance at the ClipBar. This way, I can always tell at a glance what will show up if I paste into something I'm writing.
If I could find another program that offered these two features and a responsive developer, I might switch. But for now, ClipMate meets my needs better than any other program I know.