Michael Rubin announced that internally Google had decided to move from ext2 to ext4 after careful consideration of ext4, IBM’s JFS, and SGI’s XFS.
Along with this, Google hired Theodore T’so, the man behind ext2 and ext4 to help with the migration.
The decision came down to between XFS and ext4, and the easier migration to ext4 was the deciding factor for Google. I am partial to XFS – it’s older and is perhaps more stable – but ext4 should be good as well.
I switched to OpenSUSE at one time because they offered XFS and Red Hat did not – and converted a Red Hat 7.1 install to XFS as well. Never had any problems with either installation at all.