Depends on what you expect. ext2 is quite fast. Its one of the most traditional, and has been around for some time. But journalled filesystems are much more reliable. As a general rule, go for these.
Journalled: ext3, reiserFS, jfs and xfs.
Not journalled: ext2.
If a partition is small, though, prefer ext2. The journal takes some space.
This is quite a good reading: