ComicRack is a one-stop comic viewer and manager.
It can open the regular CBR, CBZ, CBT and CB7s, all the matching archives, DJVU and PDF files. Or you might open several files and they'll each be displayed in tabs for easier access.
A toolbar gives you plenty of viewing and navigation options: single/ dual page layout, lots of fit and zoom options, manual and automatic rotation, page and bookmark navigation buttons, and more.
A versatile library system helps you manage and browse even the largest comic collection. We could more than fill the page just talking about what it can do, but as an example, it comes with built-in Smart Lists to help you locate certain comics (My Favorites, Recently Added, Recently Read, Never Read, Reading, Read, Files to update), and you can build more Lists in just a few clicks.
If you don't want to build a separate library, ComicRack's "Folders" pane provides an Explorer-type view on your drive, allowing you to browse folders and displaying thumbnails for any supported files.
A built-in batch conversion module gives you more options than most specialist tools. You can set up a custom file naming scheme, define the pages to include or exclude, set image format/ size/ quality, automatically optimise contrast or even apply your brightness, contrast, saturation, gamma and sharpening tweaks.
ComicRack is also available for Android, and there's a $7.99 iPad version, but these aren't just lesser stand-alone apps. They're designed to work together, so you can manage your collection on the PC, then sync comics for viewing on your mobile device.
After finally getting my hands on a computer with an Ultra HD display (a MacBook Pro 13 with a Retina Display), I have updated ComicRack with correct handling of high density resolutions.
ComicRack takes a while to learn, and isn't a good choice if you just want to view an occasional CBZ. It's not updated much, either. But if you're a real comic fan and will be using it all the time, there's nothing else as powerful around.