I've used more clipboard managers than I care to remember, but I've yet to find a solution that's as simple or intuitive as the rudimentary one baked into OS X. But Paste might be the first one that sticks around past the trial period.
For one, Paste's interface is stunning. Accessible via the menu bar or a logical Shift+Command+V shortcut, the app operates in a Mission Control-style layer just under the desktop. Anything you add to your clipboard gets stored in Paste's chronological collection of miniature cards that offer a fantastic at-a-glance view of not just what was copied, but when and where as well.
Your library of clips can be as large as you want (though anything beyond 100 will likely have a noticeable effect on your disk space), and zipping through them is easy thanks to its iOS-style carousel scrolling. But as my cards piled up, the lack of basic features like search and favoriting became increasingly apparent.
The whole process is very smooth and I was quickly able to incorporate it into my writing routine. To insert something into an app simply double-click one of the cards to copy the content back to your clipboard, and you can also choose to automatically paste it into the active application.
Serious clipboarders might want to wait a few revisions, but Paste's unsurpassed interface and OS X integration make it a standout even among its more powerful peers.