eLPuSHeR said:
Adobe Reader is bloated. Foxit Reader is a good alternative (pay attention to installation options). Its PDF printer is a nice addition too (you can configure preferred compression and such, unlike Microsoft's one). Sumatra is good too if you only want a barebones PDF reader (it reads Ebook formats too by the way).

PDF Xchange Viewer is my default PDF reader. It's lightweight and it allows you to export PDF as images. Not all PDFs render fine though and it's a discontinued product (even if it is still receiving updates). PDF Xchange Viewer can read Adobe Illustrator files (.AI) too, by the way.

PDF-XChange Reader also had a lot of PDF manipulation features built in, even to the free version. In the end they just dropped the other shoe and turned the freeware version of PDF-XChange Editor into the reader replacement.

This is plus plus because there are even more PDF manipulation functions which are unlocked in the freeware version of the editor. Both come in "portable" versions which do not alter file associations and store all settings in a data file rather than the registry.